A forming cavity of a laser additive manufacturing apparatus and use thereof

Abstract

The application discloses a forming cavity of a laser additive manufacturing device and application thereof, and relates to the technical field of laser additive manufacturing. The forming cavity is sequentially divided into a forming area, a powder removing area and a sintering area from bottom to top. The forming area is provided with a lifting workbench, the lifting workbench comprises a telescopic support frame and a metal base plate arranged on the telescopic support frame, the telescopic support frame is arranged at the bottom of the forming area, and the bottom surface of the work base plate is provided with a vibrator. An induction sintering furnace is arranged in the sintering area, the upper part of the induction sintering furnace is closed by electric couple filaments, the lower part of the electric couple filaments on both sides is in contact with the metal base plate which is lifted to the height to ensure that the circuit is unobstructed, and the cavity wall of the forming area is provided with a laser working window. The forming cavity of the laser additive manufacturing device of the application adds the powder removing area and the sintering area in addition to the original forming area, so that the process of additive manufacturing of high-performance diamond tools is simplified.

Description

Technical Field

[0001] This invention relates to the field of laser additive manufacturing technology, and in particular to a forming cavity for laser additive manufacturing equipment and its application. Background Technology

[0002] In modern industry, diamond tools of various shapes and structures are often manufactured using materials such as metals, ceramics, and resins as the matrix and diamond as an additive to meet diverse processing needs. Among these, metal-based, ceramic-based, and metal-ceramic composite diamond tools are the most common in industrial applications. Traditional diamond tool manufacturing methods include sintering, electroplating, and welding, each with its own advantages and currently enabling mass production of diamond tools. However, as industrial demands for diamond tools become increasingly complex in shape, precise in structure, and diverse in function, traditional manufacturing methods are finding it increasingly difficult to meet the requirements for producing high-performance tools.

[0003] Therefore, in recent years, researchers both domestically and internationally have combined additive manufacturing technology with the production requirements of diamond tools. Through methods such as laser powder bed melting, direct ink writing, and material extrusion melting, they have experimentally manufactured numerous diamond tools, including eight-sided through-hole grinding wheels, grid-like drill bits, and ultra-thin saw blades. Additive manufacturing technology integrates advanced manufacturing concepts such as reducing three-dimensional manufacturing to two-dimensional manufacturing and material-structure integration. During processing, it offers high freedom of forming, is not constrained by molds, and allows for relatively free design of raw material composition in different areas. Therefore, diamond tools produced using additive manufacturing technology often possess excellent characteristics such as complex shapes and precise structures, and can specifically solve technical challenges caused by complex application environments and special processing objects. Among various additive manufacturing methods, laser powder bed melting technology is widely used and relatively mature. It can selectively scan the powder bed with a laser to achieve integrated forming of complex-shaped, regionally controllable metal-based / ceramic-based / metal-ceramic diamond tools.

[0004] However, diamond is an allotrope of carbon and readily undergoes graphitization at high temperatures, losing its original excellent physical and mechanical properties such as hardness, strength, and thermal conductivity. When using laser powder bed melting technology to directly form diamond tools, the laser supplies high-intensity, instantaneous energy to the powder bed to be formed. The powder scanned by the laser absorbs the light energy, converting part of it into internal energy, and a large amount of heat instantly accumulates in these laser-scanned areas. This heat is sufficient to melt the metal powder, and the diamond within the metal matrix is ​​easily exposed to a high-temperature environment exceeding 1000°C, thus undergoing graphitization. Therefore, although laser powder bed melting technology offers high freedom in forming diamond tools and has significant advantages in shape design, the heat provided by the laser as an energy source to the material being processed is extremely harmful to diamond. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned shortcomings of the prior art by proposing a forming cavity for a laser additive manufacturing device and its application.

[0006] The present invention provides a forming cavity for a laser additive manufacturing apparatus, wherein the forming cavity is divided into a forming zone, a powder removal zone, and a sintering zone from bottom to top;

[0007] The forming area is provided with a lifting worktable, which includes a telescopic support frame and a metal base plate disposed on the telescopic support frame. The telescopic support frame is disposed at the bottom of the forming area, and a vibrator is disposed on the bottom surface of the work plate.

[0008] The sintering zone is equipped with an induction sintering furnace. The upper thermocouple wire of the induction sintering furnace is closed, and the lower thermocouple wires on both sides are in contact with the metal substrate that has risen to that height to ensure that the circuit is unobstructed.

[0009] The cavity wall of the forming area is provided with a laser working window.

[0010] Furthermore, the forming cavity is provided with an inert gas inlet.

[0011] Furthermore, a low-power laser with a rated power of 500W and a high-power laser with a rated power of 1000-2000W are provided outside the forming area, and the laser enters the forming area through the laser working window.

[0012] Furthermore, a galvanometer system is provided within the forming area to control the scanning path of the laser emitted by the low-power laser.

[0013] Furthermore, the low-power laser is placed at a 45° angle upwards, while the high-power laser is placed horizontally.

[0014] Furthermore, a circulating fan is provided on the side of the powder removal zone to blow the powder shaken off by vibration away from the metal substrate; and / or,

[0015] The telescopic support frame has 2 to 6 supports, and the vibrator has 6 to 12 components; and / or,

[0016] The telescopic support frame is raised and lowered by computer control software; and / or...

[0017] The metal substrate is connected to the upper end of the telescopic support frame via a thread; and / or

[0018] The vibrator is placed on the bottom surface of the metal substrate and contains a remote control receiver. It can be started and stopped remotely from the outside of the forming cavity to achieve high-frequency, low-amplitude vibration.

[0019] An integrated additive manufacturing equipment that includes the forming cavity of the laser additive manufacturing equipment described above, comprising forming-sintering.

[0020] A method for preparing diamond tools using the above-mentioned integrated forming-sintering additive manufacturing equipment includes the following steps:

[0021] Step S1, Structural Model Design

[0022] Construct a 3D model of the diamond tool that meets the usage requirements, import the 3D model into the additive manufacturing equipment, and perform slicing and layering processing on the 3D model;

[0023] Step S2, Additive Manufacturing Material Preparation

[0024] Based on the usage scenarios and application conditions of diamond tools, a suitable matrix material is designed and selected and mixed with diamond in a certain proportion to obtain metal matrix diamond composite powder.

[0025] Step S3, laser scanning forming

[0026] The metal-based diamond composite powder is fed into the metal substrate of the forming cavity, and the metal-based diamond composite powder bed is rapidly scanned to form a diamond tool layer by layer.

[0027] Step S4, in-situ vibration dust removal

[0028] After the low-power laser scans the last layer of powder bed, the metal substrate supporting the powder bed is lifted by the telescopic support frame, so that the height of the diamond tool on the metal substrate rises to the powder removal area located directly above the forming area. The vibrator is turned on to make the metal substrate vibrate up and down to remove the unscanned powder inside the formed diamond tool and prevent it from sticking to the main body of the diamond tool during the later sintering.

[0029] After the in-situ vibration ends, the metal substrate continues to be raised to the sintering zone located directly above the powder removal zone;

[0030] Step S5, In-cavity sintering

[0031] After the diamond tool on the metal substrate is lifted to the sintering zone, inert gas continues to be introduced into the additive manufacturing forming cavity to keep the oxygen content in the forming cavity below 200ppm. The medium frequency sintering induction furnace in the sintering zone causes the temperature of the sintering zone to rise to the melting temperature of the metal matrix.

[0032] Step S6, laser cutting

[0033] After the sintering in the cavity is completed, the metal substrate is lowered to the initial height of the forming scan, and the high-power laser is turned on to detach the diamond tool from the metal substrate; the forming cavity is then opened, thus obtaining a diamond tool with a specific structure and strength.

[0034] Furthermore, in step S1, the appropriate diamond particle size, concentration, crystal form, and distribution in the matrix material are designed, and the corresponding macroscopic structure of the diamond tool is designed according to the requirements of the industrial application scenario; and / or,

[0035] In step S2, the matrix material powder has a sphericity ≥95%, flowability ≤30s / 50g, oxygen content ≤800ppm, and a particle size range of 15~53um; the prepared matrix material is dried for use; and / or,

[0036] The specific operation of step S3 is as follows: To avoid graphitization of diamond, first turn on a low-power laser with a rated power of 50W, optimize the laser forming parameters, and use a low-power, high-speed laser to quickly scan the metal-based diamond composite powder bed, forming a diamond tool layer by layer; and / or, in step S5, the sintering heating rate is 10-100℃ / min, and after reaching the set temperature, the holding time is 5-10min. The cooling method is furnace cooling, and during the cooling process, either nitrogen or argon is continuously introduced to ensure that the formed sample is in an oxygen environment below 500ppm, reducing the oxidation of the matrix material and thermal damage to the diamond; and / or,

[0037] In step S6, a 1000-2000W high-power laser is turned on, and a high-power laser with a spot diameter of 150µm is used to scan along the interface between the metal substrate and the diamond tool.

[0038] A diamond tool prepared using the above-described method for preparing diamond tools.

[0039] This invention modifies the forming cavity of traditional commercial laser additive manufacturing equipment, adding a powder removal zone and a sintering zone in addition to the original forming zone. This simplifies the process of additive manufacturing high-performance diamond tools and makes their commercial application and mass production possible.

[0040] This invention optimizes the process flow for additive manufacturing diamond tools. While maintaining the high degree of freedom in manufacturing additively formed diamond tools, it avoids the need for secondary sintering after removing the additively manufactured workpiece through a pre-forming and then sintering process. This allows the diamond tool to be integrally formed within the forming cavity of the additive manufacturing equipment, and includes a protective gas to prevent oxidation of the metal matrix at high temperatures and to prevent the diamond from rapidly graphitizing upon contact with oxygen. This ensures that the diamond tool contains specific complex and precise structures while mitigating the performance loss caused by thermal damage to the diamond. It provides the possibility for the integral forming of high-performance, complex, and precise structural parts.

[0041] This invention provides a processing method with high degree of freedom in forming and minimal thermal damage to diamond, in order to reduce diamond graphitization and fully utilize the high degree of freedom processing characteristics of laser powder bed melting to obtain diamond tools with high matrix holding force, controllable shape and structure, and strong stability in use. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the forming cavity of the laser additive manufacturing equipment of the present invention;

[0043] Figure 2 This is a schematic diagram of the lifting worktable of the present invention located in the dust removal zone;

[0044] Figure 3 This is a schematic diagram of the lifting worktable of the present invention located in the sintering zone.

[0045] 1. Forming zone; 2. Powder removal zone; 21. Circulating fan; 3. Sintering zone; 4. Lifting worktable; 41. Telescopic support frame; 42. Metal substrate; 5. Vibrator; 6. Sintering induction furnace; 61. Electrocouple wire; 7. Low-power laser; 8. Galvanometer system; 9. High-power laser. Detailed Implementation

[0046] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0047] like Figure 1-3 As shown, the forming cavity of a laser additive manufacturing device of the present invention is divided into a forming zone 1, a powder removal zone 2 and a sintering zone 3 from bottom to top.

[0048] The forming area 1 is provided with a lifting worktable 4. The lifting worktable 4 includes a telescopic support frame 41 and a metal substrate 42 disposed on the telescopic support frame 41. The telescopic support frame 41 is disposed at the bottom of the forming area 1, and a vibrator 5 is disposed on the bottom surface of the work substrate. The telescopic support frame 41 raises the metal substrate 42 to the powder removal area 2, and then the vibrator 5 is activated to remove residual powder on the worktable metal substrate 42 by high-frequency low-amplitude vibration.

[0049] Sintering zone 3 is the working area for sintering the formed sample on the metal substrate 42 by heating in a medium-frequency induction sintering furnace 6. The medium-frequency induction sintering furnace is placed in sintering zone 3. The upper thermocouple wire 61 of the induction sintering furnace is closed, and the lower thermocouple wires 61 on both sides are in contact with the metal substrate 42 that has risen to that height to ensure that the circuit is unobstructed. The medium-frequency induction sintering device is a commonly used device in the industrial market, and its maximum heating temperature can reach 1500℃.

[0050] A laser working window can be provided on the cavity wall of forming area 1 for laser processing.

[0051] The forming cavity may be provided with an inert gas inlet for introducing inert gas into the forming cavity.

[0052] Outside the forming area 1, a low-power laser 7 with a rated power of 500W and a high-power laser 9 with a rated power of 1000-2000W can be installed. The laser enters the forming area 1 through the laser working window. The low-power laser 7 with a rated power of 50W is turned on, and the laser forming parameters are optimized. A low-power, high-speed laser is used to quickly scan the metal-based diamond composite powder bed, forming a diamond tool layer by layer. The high-power laser 9 with a rated power of 1000-2000W is turned on, and a high-power laser with a spot diameter of 150µm is used to scan along the interface between the metal substrate 42 and the diamond tool. The metal at the interface rapidly vaporizes, causing the diamond tool to detach from the metal substrate 42.

[0053] The low-power laser 7 can be placed at a 45° angle upwards, and a galvanometer system 8 can also be installed in the forming area 1 to control the scanning path of the laser emitted by the low-power laser 7. The high-power laser 9 is placed horizontally to facilitate scanning along the interface between the metal substrate 42 and the diamond tool.

[0054] A circulating fan 21 can be provided on the side of the powder removal area 2 to blow the powder shaken off by vibration away from the metal substrate 42.

[0055] The telescopic support frame 41 has 2 to 6 supports to ensure stability during lifting and lowering, and the vibrators 5 have 6 to 12 supports to ensure effective powder dispersal. The lifting and lowering of the telescopic support frame 41 can be controlled by computer control software. The metal substrate 42 and the upper end of the telescopic support frame 41 can be connected by threads; the vibrators 5 are installed on the lower surface of the metal substrate 42 and contain a remote control receiver, which can be remotely started and stopped from the outside of the forming cavity to achieve high-frequency, low-amplitude vibration.

[0056] An integrated additive manufacturing equipment that includes the forming cavity of the laser additive manufacturing equipment described above, comprising forming-sintering.

[0057] The forming cavity of this invention, together with commercially available additive manufacturing equipment such as powder feeding devices, industrial computer mechanical control systems, additive manufacturing control software, gas circulation systems, laser generation and control systems, and powder and impurity filtration systems, constitutes an integrated forming-sintering additive manufacturing equipment. It should be understood that, except for the forming working cavity of the laser powder bed melting equipment, the other functional systems have relatively mature applications in the industrial field, and those skilled in the art, after training, can assemble the various systems to meet industrial usage requirements.

[0058] A method for preparing diamond tools using the above-mentioned integrated forming-sintering additive manufacturing equipment includes the following steps:

[0059] The process includes structural model design, additive manufacturing material preparation, laser scanning forming, intracavity vibration powder removal, intracavity sintering, and laser cutting.

[0060] Step S1, Structural Model Design

[0061] Construct a 3D model of the diamond tool that meets the usage requirements, design the diamond grain size, concentration, crystal form and distribution in the matrix material, and design the corresponding macroscopic structure of the diamond tool according to the needs of industrial application scenarios. Import the 3D model into the additive manufacturing equipment and perform slicing and layering processing on the 3D model.

[0062] Step S2, Additive Manufacturing Material Preparation

[0063] Based on the usage scenarios and application conditions of diamond tools, a suitable matrix material composition is designed and selected. Common matrix material metals include iron, copper, nickel, titanium, and cobalt-based alloys. The matrix material powder has a sphericity ≥95%, flowability ≤30s / 50g, oxygen content ≤800ppm, and a particle size range of 15–53µm. The prepared matrix material is dried for use.

[0064] Furthermore, the matrix material prepared by gas atomization is weighed with diamond in proportion and placed in a mixer for uniform mixing to obtain metal-diamond composite powder.

[0065] Step S3, laser scanning forming

[0066] The metal-based diamond composite powder is fed into the additive manufacturing equipment. To prevent the diamond from graphitizing, a low-power laser 7 with a rated power of 50W is first turned on, the laser forming parameters are optimized, and a low-power, high-speed laser is used to quickly scan the metal-based diamond composite powder bed, forming a diamond tool layer by layer.

[0067] Step S4, in-situ vibration dust removal

[0068] After the low-power laser scans the last layer of powder bed, the support frame of the metal substrate 42 supporting the powder bed is raised, causing the diamond tool on the metal substrate 42 to rise to the powder removal zone 2 located directly above the forming zone 1. The vibrator 5 is then activated, causing the metal substrate 42 to vibrate up and down to remove unscanned powder from inside the formed diamond tool, preventing it from sticking to the main body of the diamond tool during subsequent sintering. After the in-situ vibration ends, the metal substrate 42 continues to be raised to the sintering zone 3 located directly above the powder removal zone 2.

[0069] Step S5, In-cavity sintering

[0070] After the diamond tool on the metal substrate 42 is lifted to the sintering zone 3, inert gas continues to be introduced into the additive manufacturing equipment to maintain the oxygen content in the forming cavity below 200 ppm. The medium-frequency induction furnace 6 in the sintering zone 3 raises the temperature of the sintering zone 3 to the melting temperature of the metal matrix. The powder at the weak points of the weak metal matrix, which was originally formed by low-power laser scanning, melts and then solidifies, resulting in a significant increase in strength. During the sintering process, heat conduction is the main energy exchange method. The thermal environment of the diamond does not reach its graphitization temperature, and being in an inert gas environment reduces thermal damage to the diamond.

[0071] During sintering, either argon or nitrogen is continuously introduced into the working chamber to keep the formed sample in an oxygen environment of less than 500 ppm.

[0072] Preferably, during sintering, no external pressure is applied to the formed sample to protect its original shape from change;

[0073] Preferably, the sintering heating rate is 10-100℃ / min, and after reaching the set maximum temperature, the holding time is 5-10min. The cooling method is furnace cooling. During the cooling process, either nitrogen or argon is continuously introduced so that the formed sample is in an oxygen environment of less than 500ppm, thereby reducing the oxidation of the matrix material and thermal damage to the diamond.

[0074] Step S6, laser cutting

[0075] After intracavitary sintering is completed, the metal substrate 42 is lowered to the initial height of the forming scan. A high-power laser 9 of 1000–2000W is turned on, and a high-power laser with a spot diameter of 150µm is used to scan along the interface between the metal substrate 42 and the diamond tool. The metal at the interface rapidly vaporizes, causing the diamond tool to detach from the metal substrate 42. The forming cavity of the additive manufacturing equipment is then opened, resulting in a diamond tool with a specific structure and strength.

[0076] The preparation method of this application will now be described using specific components.

[0077] Example 1

[0078] The proposed solution is to manufacture a diamond drill bit for drilling cores from hard, dense, and weakly abrasive formations, with a core size requirement of 91 mm in diameter.

[0079] Step S1, Structural Model Design

[0080] A 3D model of a diamond tool meeting usage requirements was constructed according to the design and manufacturing specifications for drill bits and drilling tools such as GB / T 16950. The core drill bit mainly consists of two parts: the drill bit body and the working layer. Based on the requirements for core drilling in geological exploration, the drill bit body and the working layer are designed according to the standard dimensions of diamond core drill bits. The structure and model of the diamond core drill bit used for drilling cores from hard, dense, and weakly abrasive formations are not the core inventive point of this invention, and therefore will not be described in detail.

[0081] Furthermore, the 3D model of the core drill bit is imported into the additive manufacturing equipment control system, and the slicing software automatically processes the 3D model data and divides it into several slicing surfaces.

[0082] Step S2, Additive Manufacturing Material Preparation

[0083] The manufacturing of the rigid body of diamond core drill bits requires the use of commercial 316 stainless steel alloy, with powder sphericity ≥95%, flowability 20s / 50g, and oxygen content 500ppm.

[0084] Furthermore, the product to be manufactured and processed in this embodiment is a diamond core drill bit. The target formation is a hard, dense, and weakly abrasive formation. A copper-based alloy is selected as the matrix material for manufacturing the working layer of the diamond drill bit. The alloy material composition is copper (80wt%), tin (10wt%), and titanium (10wt%). The sphericity of the copper-based alloy matrix material powder is ≥95%, the flowability is ≤30s / 50g, the oxygen content is ≤800ppm, and the powder particle size range is 15~53um.

[0085] Furthermore, diamond occupies 20% of the working layer volume of the core drill bit, and the diamond is a perfect tetradecahedral crystal with a grain size of 38-44 μm.

[0086] Furthermore, diamond and copper-based alloy are mixed in a mixer at a volume ratio of 1:4 for 10 hours to ensure that the diamond is evenly dispersed in the copper-based alloy matrix.

[0087] Furthermore, the 316 stainless steel powder and copper-based diamond composite powder are dried and kept for later use.

[0088] Step S3, laser scanning forming

[0089] 316 stainless steel powder is fed into the additive manufacturing equipment. The powder is spread using the powder spreading scraper built into the equipment, with a powder layer thickness of 50µm. A low-power laser 7 with a rated power of 500W is turned on, with the laser scanning speed set to 750mm / s, the laser power set to 350W, and the scanning interval set to 0.12mm. Argon gas is introduced as a protective gas to keep the oxygen content in the forming zone 1 below 300ppm. The core drill bit is formed layer by layer.

[0090] Furthermore, after the core drill bit body is formed, the powder in the powder cylinder of the additive manufacturing equipment is replaced, and the dried copper-based diamond composite material is loaded into the powder cylinder. A layer of composite material powder is laid on the upper surface of the core drill bit body, with a powder layer thickness of 50um.

[0091] Furthermore, argon gas is continuously introduced as a protective gas to reduce the oxygen content in forming zone 1 to 100 ppm. The laser scanning speed is set to 1200 mm / s, the laser power is set to 30 W, the scanning interval is 0.08 mm, and the low-power laser 7 is turned on to scan the forming core drill bit working layer by layer.

[0092] Step S4, in-situ vibration dust removal

[0093] After the low-power laser scans the last layer of copper-based diamond composite powder bed, the metal substrate 42 supporting the powder bed is raised, causing the diamond tool on the metal substrate 42 to rise to the powder removal zone 2 located directly above the forming zone 1. Eight vibrators 5 are turned on to make the metal substrate 42 vibrate at a high frequency. At the same time, two powerful dust removal fans located on the side wall of the powder removal zone 2 are turned on to accelerate the powder flow and remove the unscanned powder inside the formed diamond tool.

[0094] Furthermore, after the in-situ vibration ends, the metal substrate 42 continues to rise to the sintering zone 3 located directly above the dust removal zone 2.

[0095] Step S5, In-cavity sintering

[0096] After the core drill bit is raised to sintering zone 3, argon gas continues to be introduced into the additive manufacturing forming equipment to maintain the oxygen content in the forming cavity below 200 ppm. The medium-frequency induction furnace 6 in sintering zone 3 starts working, causing the temperature in the working layer of the core drill bit to rise to the melting temperature of the copper-based alloy. The powder at the weak points of the copper-based alloy, which was originally formed by low-power laser scanning, melts and then solidifies, significantly increasing the bending strength to 700 MPa to meet the strength requirements.

[0097] Preferably, the sintering curve is designed according to the conventional sintering method, with a heating rate of 30℃ / min, a maximum design temperature of 1000℃, a holding time of 5min, and the core drill bit is cooled with the furnace after the holding time is completed.

[0098] Step S6, laser cutting

[0099] After the intracavity sintering is completed, the metal substrate 42 is lowered to the initial height of the forming scan. The 2000W high-power laser 9 is turned on, and a 2000W high-power laser with a spot diameter of 150µm is used to scan along the interface between the metal substrate 42 and the lower end of the core drill bit. The metal at the interface rapidly vaporizes, causing the core drill bit to detach from the metal substrate 42. After the metal substrate 42 and the core drill bit cool to 25°C, the forming cavity of the additive manufacturing equipment is opened, and the diamond core drill bit is removed.

[0100] Example 2

[0101] The plan is to manufacture metal-based diamond grinding heads for grinding cemented carbide.

[0102] Step S1, Structural Model Design

[0103] The dimensions and structure of the diamond grinding head are designed in accordance with relevant national standards such as GB / T 41403-2022. The structural model design of the diamond grinding head is not the core inventive point of this invention, so it will not be described in detail.

[0104] Furthermore, the 3D model of the grinding head is imported into the control system of the additive manufacturing equipment, and the slicing software automatically processes the 3D model data and divides it into several slicing surfaces.

[0105] Step S2, Additive Manufacturing Material Preparation

[0106] The product to be manufactured and processed in this embodiment is a diamond grinding head. The processing object of the product is a brittle material such as cemented carbide. A cobalt-based alloy is selected as the matrix material for manufacturing the working layer of the diamond drill bit. The alloy material composition is cobalt (66wt%), chromium (27.3wt%), molybdenum (5.9wt%), and the remainder is impurity. The sphericity of the cobalt-based alloy matrix material powder is ≥95%, the Hall flow rate is 18.1s / 50g, the oxygen content is 600ppm, and the powder particle size range is 15~53um.

[0107] Furthermore, diamond accounts for 5% of the volume of the diamond grinding head. The diamond is a perfect octahedral crystal with a grain size of 13-23 μm.

[0108] Furthermore, diamond and cobalt-based alloy were mixed in a mixer at a volume ratio of 1:19 for 10 hours to ensure that diamond was uniformly dispersed in the cobalt-based alloy matrix.

[0109] Furthermore, the cobalt-based diamond composite powder is dried for later use.

[0110] Step S3, laser scanning forming

[0111] Cobalt-based diamond composite powder is fed into an additive manufacturing equipment. The powder is spread using a powder spreading scraper built into the equipment, with a powder layer thickness of 50 μm. A low-power laser 7 with a rated power of 500 W is turned on, with the laser scanning speed set to 900 mm / s, the laser power set to 50 W, and the scanning interval set to 0.15 mm. Argon gas is introduced as a protective gas to keep the oxygen content in the forming zone 1 below 300 ppm. The diamond grinding head is formed by scanning layer by layer.

[0112] Step S4, in-situ vibration dust removal

[0113] After the low-power laser scans the last layer of cobalt-based diamond composite powder bed, the metal substrate 42 supporting the powder bed is raised, causing the diamond tool on the metal substrate 42 to rise to the powder removal zone 2 located directly above the forming zone 1. Six vibrators 5 are turned on to make the metal substrate 42 vibrate at a high frequency. At the same time, two powerful dust removal fans located on the side wall of the powder removal zone 2 are turned on to accelerate the powder flow and remove the unscanned powder inside the formed diamond tool.

[0114] Furthermore, after the in-situ vibration ends, the metal substrate 42 continues to rise to the sintering zone 3 located directly above the dust removal zone 2.

[0115] Step S5, In-cavity sintering

[0116] After the diamond grinding head is raised to sintering zone 3, argon gas continues to be introduced into the additive manufacturing forming equipment to maintain the oxygen content in the forming cavity below 200 ppm. The medium-frequency induction furnace 6 in sintering zone 3 then begins operation, causing the temperature inside the diamond grinding head to rise to the melting temperature of the cobalt-based alloy. The powder at the weak points of the weak cobalt-based alloy, which was originally formed by low-power laser scanning, melts and then solidifies, significantly increasing the bending strength to 1000 MPa to meet the strength requirements.

[0117] Preferably, the sintering curve is designed according to the conventional sintering method, with a heating rate of 40℃ / min, a maximum design temperature of 1200℃, a holding time of 5min, and the diamond grinding head is cooled with the furnace after the holding time is completed.

[0118] Step S6, laser cutting

[0119] After the intracavity sintering is completed, the metal substrate 42 is lowered to the initial height of the forming scan. The 2000W high-power laser 9 is turned on, and a 2000W high-power laser with a spot diameter of 100µm is used to scan along the interface between the metal substrate 42 and the lower end of the diamond grinding head. The metal at the interface rapidly vaporizes, causing the diamond grinding head to detach from the metal substrate 42. After the metal substrate 42 and the diamond grinding head cool to 25°C, the forming cavity of the additive manufacturing equipment is opened, and the diamond grinding head is removed.

[0120] For any points not covered above, existing technologies shall apply.

[0121] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A forming cavity for a laser additive manufacturing device, characterized in that: The forming cavity is divided into a forming zone, a powder removal zone, and a sintering zone from bottom to top; The forming area is provided with a lifting worktable, which includes a telescopic support frame and a metal base plate disposed on the telescopic support frame. The telescopic support frame is disposed at the bottom of the forming area, and a vibrator is disposed on the bottom surface of the metal base plate. The sintering zone is equipped with an induction sintering furnace. The upper thermocouple wire of the induction sintering furnace is closed, and the lower thermocouple wires on both sides are in contact with the rising metal substrate to ensure that the circuit is unobstructed. The cavity wall of the forming area is provided with a laser working window; The forming cavity is provided with an inert gas inlet; The forming area is equipped with a low-power laser with a rated power of 500W and a high-power laser with a rated power of 1000~2000W. The laser enters the forming area through the laser working window. The forming area is equipped with a galvanometer system to control the scanning path of the laser emitted by the low-power laser. The low-power laser is placed at a 45° angle upwards, while the high-power laser is placed horizontally. A circulating fan is provided on the side of the powder removal zone to blow the powder shaken off by vibration away from the metal substrate.

2. The forming cavity of a laser additive manufacturing equipment as described in claim 1, characterized in that: The number of telescopic support frames is 2 to 6, and the number of vibrators is 6 to 12.

3. The forming cavity of a laser additive manufacturing equipment as described in claim 1, characterized in that: The telescopic support frame is raised and lowered by computer control software.

4. The forming cavity of a laser additive manufacturing equipment as described in claim 1, characterized in that: The metal substrate is connected to the upper end of the telescopic support frame by threads.

5. A forming-sintering integrated additive manufacturing apparatus comprising the forming cavity of the laser additive manufacturing apparatus according to any one of claims 1-4.

6. A method for preparing diamond tools using the integrated forming-sintering additive manufacturing equipment as described in claim 5, characterized in that: Includes the following steps: Step S1, Structural Model Design Construct a 3D model of a diamond tool that meets the usage requirements, import the 3D model into the additive manufacturing equipment, and perform slicing and layering processing on the 3D model; Step S2, Additive Manufacturing Material Preparation Based on the usage scenarios and application conditions of diamond tools, a suitable matrix material is designed and selected and mixed with diamond in a certain proportion to obtain metal matrix diamond composite powder. Step S3, laser scanning forming The metal-based diamond composite powder is fed into the metal substrate of the forming cavity, and the metal-based diamond composite powder bed is rapidly scanned to form a diamond tool layer by layer. The specific operation of step S3 is as follows: In order to avoid graphitization of diamond, first turn on a low-power laser with a rated power of 500W, optimize the laser forming parameters, and use a low-power high-speed laser to quickly scan the metal-based diamond composite powder bed, and scan and form a diamond tool layer by layer. The laser scanning speed is 750mm / s or 900mm / s; Argon gas is introduced as a protective gas to keep the oxygen content in the forming area below 300ppm. Step S4, in-situ vibration dust removal After the low-power laser scans the last layer of powder bed, the metal substrate supporting the powder bed is lifted by the telescopic support frame, so that the height of the diamond tool on the metal substrate rises to the powder removal area located directly above the forming area. The vibrator is turned on to make the metal substrate vibrate up and down to remove the unscanned powder inside the formed diamond tool and prevent the unscanned powder from sticking to the main body of the diamond tool during the later sintering. After the in-situ vibration ends, the metal substrate continues to be raised to the sintering zone located directly above the powder removal zone; Step S5, In-cavity sintering After the diamond tool on the metal substrate is lifted to the sintering zone, argon gas continues to be introduced into the forming cavity of the additive manufacturing equipment to keep the oxygen content in the forming cavity below 200ppm. The medium frequency induction sintering furnace in the sintering zone causes the temperature of the sintering zone to rise to the melting temperature of the metal matrix. Step S6, laser cutting After the sintering in the cavity is completed, the metal substrate is lowered to the initial height of the forming scan, and the high-power laser is turned on to detach the diamond tool from the metal substrate; the forming cavity is then opened, thus obtaining a diamond tool with a specific structure and strength.

7. The method for preparing diamond tools as described in claim 6, characterized in that: In step S1, the appropriate diamond particle size, concentration, crystal form, and distribution in the matrix material are designed, and the corresponding macroscopic structure of the diamond tool is designed according to the requirements of the industrial application scenario; and / or, In step S2, the matrix material powder has a sphericity ≥95%, flowability ≤30s / 50g, oxygen content ≤800ppm, and a particle size range of 15~53um; the prepared matrix material is dried for use; and / or, In step S5, the sintering heating rate is 10~100℃ / min. After reaching the set temperature, the holding time is 5~10min. The cooling method is furnace cooling. During the cooling process, argon gas continues to be introduced so that the formed diamond tool is in an oxygen environment below 500ppm, reducing the oxidation of the matrix material and thermal damage to the diamond; and / or, In step S6, a 1000~2000W high-power laser is turned on, and a high-power laser with a spot diameter of 150um is used to scan along the interface between the metal substrate and the diamond tool.

Images