A 3D printing forming ceramic degreasing and sintering integrated furnace

Abstract

The utility model discloses a kind of for 3D printing forming ceramic glue discharge sintering integrated furnace. The integrated furnace includes furnace body, support structure, lifting drive mechanism, sealing assembly and atmosphere supply pipeline. Sealing assembly is constituted by mobile sealing unit and sealing tube, and closed space can be formed in furnace body by lifting. Operating method includes charging, closed space formation, atmosphere replacement, glue discharge, carbon discharge, sintering and cooling step, realizes integrated continuous processing of whole process. The utility model avoids greenware transfer injury by dynamic sealing technology, significantly improves yield and production efficiency, reduces equipment investment and energy consumption, solves the core problem existing in traditional step-by-step processing.

Description

Technical Field

[0001] This utility model relates to the field of inorganic non-metallic ceramic sintering equipment, and in particular to an integrated furnace for debinding and sintering 3D printed ceramics. Background Technology

[0002] 3D printing technology, especially photopolymer-based ceramic slurry 3D printing, can directly manufacture ceramic blanks with complex geometries. However, these ceramic blanks contain a large amount of organic binders (such as photosensitive resins) and must undergo two key post-processing steps, debinding and high-temperature sintering, to obtain dense final ceramic parts.

[0003] Currently, in the field of ceramic material debinding and sintering, the mainstream industrial production method is to perform these two processes independently in different equipment. Specifically: Debinding process: This is usually carried out in a dedicated debinding furnace. This process requires a specific atmosphere (such as inert gas, vacuum) and a precisely controlled low-temperature heating curve to allow the organic components in the ceramic green body to decompose and be expelled slowly and uniformly. If the temperature rises too quickly or the atmosphere is not properly controlled, the green body is prone to cracking, blistering, or even collapse due to internal gas pressure accumulation or uneven stress. Sintering process: After debinding, the debinded but not yet densified ceramic green body needs to be transferred to another high-temperature sintering furnace (such as a vacuum sintering furnace or atmosphere sintering furnace) for densification sintering at a higher temperature to obtain the final mechanical properties and microstructure.

[0004] The existing step-by-step processing mode has significant drawbacks: the ceramic green body after debinding has extremely low strength. During the multiple transfer operations from the debinding furnace to the sintering furnace, it is very easy to develop micro-cracks or break directly due to mechanical vibration, human touch, or its own gravity. This is the main factor causing the low yield of the final ceramic parts. At the same time, this mode leads to a long production cycle, low equipment utilization, and high energy consumption. It also forces companies to invest in and maintain two independent equipment systems, which significantly increases production costs. In addition, since the intermediate links involve multiple manual or mechanical transfers, many uncontrollable variables are introduced, which seriously affect the stability of the process and the consistency of the final product performance.

[0005] Therefore, there is an urgent need in this field for an innovative device that can integrate debinding and sintering processes to fundamentally avoid the transfer of raw blanks during the fragile stage, simplify the process flow, and improve production success rate and efficiency. Utility Model Content

[0006] The purpose of this invention is to provide an integrated furnace for debinding and sintering ceramics for 3D printing. This invention provides a device that integrates debinding and sintering functions. Through the synergistic effect of dynamic sealing and controllable atmosphere system, it realizes continuous processing of ceramic blanks from debinding to sintering, effectively solving the problems of low yield, long cycle and high cost caused by intermediate transfer.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] In the first aspect, this utility model provides an integrated furnace for sintering and debinding ceramics for 3D printing.

[0009] A sintering furnace for 3D printed ceramics includes: a furnace body (1) with an opening at its bottom; a support structure (5) located below the furnace body (1), through which a sintering platform (6) for supporting ceramic blanks extends into the furnace body (1) from the opening; a lifting drive mechanism (3) located below the furnace body (1); and a sealing assembly connected to the lifting action part of the lifting drive mechanism (3) and driven to move vertically along the support structure (5); the sealing assembly includes a movable sealing unit (4) and a sealing tube (2) disposed thereon; wherein the sealing assembly is configured such that when it rises to a first position, the sealing tube (2) engages with the inner wall of the furnace body (1) to form a sealed space around the sintering platform (6) inside the furnace body (1); the "engagement" can be achieved by setting a high-temperature resistant sealing ring at the top of the sealing tube (2) or by using a precision conical / planar pressing structure to ensure a sealing effect. An atmosphere supply pipeline (7) has its outlet connected to the sealed space for filling the sealed space with process gas.

[0010] In an embodiment that optimizes the aforementioned scheme, the sealing assembly can be driven down to a second position by the lifting drive mechanism (3), in which the sealing tube (2) is completely detached from the furnace body (1) and the space above the sintering platform (6) is completely open.

[0011] In an embodiment that optimizes the aforementioned scheme, a control unit (8) and a power management module (9) are further included. The control unit (8) is electrically connected to the lifting drive mechanism (3) and the atmosphere supply pipeline (7), and is configured to control the movement of the sealing assembly between the first position and the second position, and to control the process gas to be introduced into the sealed space according to a preset program. The power management module (9) is connected to the control unit (8) and is configured to provide at least two different output voltages, including a high-voltage output for powering the heating elements inside the furnace body (1), and at least one conventional voltage output for powering the control unit (8) and the lifting drive mechanism (3). A specific implementation of the power management module (9) includes a power frequency transformer, a high-frequency switching power supply, or a multi-output switching power supply. For example, the high-voltage output is 220V or 380V AC, and the conventional voltage output is 24V DC or other low-voltage safety voltage, obtained through rectification, filtering, and voltage regulation circuits inside the module.

[0012] In an embodiment that optimizes the aforementioned solution, a human-machine interface (10) is further included. The human-machine interface (10) is communicatively connected to the control unit (8) and is used to receive process parameter commands input by the user and display the operating status information of the integrated furnace. Specifically, the human-machine interface (10) may be a touch screen, a liquid crystal display with physical buttons, or terminal software that communicates with a host computer. It exchanges data with the control unit (8) via RS485, Ethernet, or CAN bus.

[0013] In an embodiment that optimizes the aforementioned scheme, the furnace body (1) includes a heat-insulating lining (1-1), a heating element (1-2) disposed inside the furnace body (1) and surrounding the periphery of the sealed space, and an electrical connection terminal (1-3) disposed on the upper part of the furnace body (1); the electrical connection terminal (1-3) is electrically connected to the heating element (1-2) and electrically connected to the high-voltage output of the power management module (9). The heat-insulating lining (1-1) can be made of lightweight refractory materials such as ceramic fiber board, polycrystalline mullite fiber blanket, or alumina hollow spherical brick. The heating element (1-2) can be a silicon molybdenum rod, silicon carbide rod, or resistance wire, and its surrounding pattern can be designed as upper and lower partitions or left and right symmetrical arrangement according to the temperature uniformity requirements.

[0014] In an embodiment that optimizes the aforementioned solution, an annular sealing structure (1-4) is provided on the inner top wall of the furnace body (1). When the sealing tube (2) rises to the first position, its top end is pressed against the annular sealing structure (1-4) to jointly form the top sealing interface of the sealed space. The annular sealing structure (1-4) can be a graphite sealing ring or an elastic sealing ring made of high-temperature resistant alloy embedded in the groove of the furnace body top wall. It achieves sealing by deforming under the positive pressure provided by the rising of the sealing tube (2).

[0015] In an embodiment that optimizes the aforementioned scheme, an external load-bearing frame (1-5) is further included. The external load-bearing frame (1-5) is disposed outside the furnace body (1), with its bottom end connected to the top structure of the furnace body (1) and its top end connected to an external fixed foundation. The external load-bearing frame (1-5) is configured to bear and transmit the force generated by the sealing assembly when the sealing pipe (2) rises and presses against the furnace body (1) for sealing, thereby preventing the force from acting directly on the heat insulation lining (1-1) and its associated structure. The external load-bearing frame (1-5) can be constructed from a gantry frame or column frame structure welded from steel profiles, square tubes, or steel plates. Its connection with the furnace body (1) and the external foundation is preferably a rigid connection method such as flange bolt connection or welding to form a stable force flow path.

[0016] In an embodiment that optimizes the aforementioned scheme, the lifting drive mechanism (3) includes a fixed base (3-1), a moving platform (3-2), a drive motor (3-3), and a transmission assembly; the drive motor (3-3) is fixed to the fixed base (3-1); the transmission assembly is connected between the output end of the drive motor (3-3) and the moving platform (3-2), and is configured to convert the rotational motion of the drive motor (3-3) into linear motion of the moving platform (3-2) in the vertical direction; except for the lead screw and nut pair described below, the "transmission assembly" can also be equivalently replaced by a linear drive mechanism such as a gear and rack mechanism, a hydraulic cylinder, or an electric push rod. The sealing assembly is disposed on the moving platform (3-2) and can move synchronously with it.

[0017] Specifically, the transmission assembly includes a lead screw and nut pair consisting of a lead screw (3-4) and a lead screw nut (3-5), and at least one set of guide shafts (3-7) for guiding the movement direction of the moving platform (3-2). One end of the lead screw (3-4) is connected to the output end of the drive motor (3-3), and the other end is supported by a lead screw seat (3-6). The lead screw nut (3-5) is fixedly mounted on the moving platform (3-2) and meshes with the lead screw (3-4). The guide shafts (3-7) are vertically mounted on the fixed base (3-1) and pass through corresponding guide holes or bearings provided on the moving platform (3-2). Linear bearings or self-lubricating copper sleeves can be installed in the guide holes to reduce friction.

[0018] Specifically, the bottom of the support structure (5) is fixed to the fixed base (3-1) of the lifting drive mechanism (3). The support structure (5) passes through the mobile platform (3-2) and the sealing component thereon and is movably engaged with the sealing component. In terms of horizontal projection, the support structure (5) is located inside the space enclosed by the drive component and the guide component of the lifting drive mechanism (3), or is closely adjacent to and parallel to it.

[0019] In an embodiment that optimizes the aforementioned scheme, the movable sealing unit (4) integrates a sealing tube mounting part, an exhaust channel, a cooling channel, and at least one dynamic seal (4-6); the sealing tube (2) is mounted on the sealing tube mounting part; the exhaust channel is configured to communicate with the sealed space and is provided with a first exhaust port (4-12) for connecting to an external vacuum device and a second exhaust port (4-7) for connecting to an external exhaust gas treatment device; the cooling channel is arranged around the exhaust channel; the dynamic seal (4-6) is disposed on the inner ring side of the movable sealing unit (4) and is configured to be activated when the sealed space is formed, so as to achieve a movable seal between the movable sealing unit (4) and the support structure (5). The core of the "dynamic seal" is that its state is controllable. In addition to the inflatable sealing ring, a hydraulically driven expansion sealing ring or an electromagnetically driven mechanical clamping mechanism can also be used. The "activation" refers to the introduction of compressed air or inert gas into the inflatable sealing ring to make it expand radially and hug the support structure (5).

[0020] Specifically, the sealing tube mounting part of the movable sealing unit (4) is a flange (4-5) for fixing the sealing tube (2); the exhaust channel is composed of an annular exhaust chamber (4-1), the top of which is provided with several gas through holes (4-11) communicating with the sealed space; the cooling channel is specifically an annular water-cooled chamber (4-2) surrounding the exhaust chamber (4-1), and its side is provided with a coolant circulation port (4-21); the dynamic seal (4-6) is an inflatable sealing ring; it is located at the bottom of the inner ring side of the movable sealing unit (4) and is provided with a sealing ring inflation port (4-61). Among them, the annular water-cooled chamber (4-2) is located above the annular exhaust chamber (4-1), and the inflatable sealing ring is located below the annular exhaust chamber (4-1). The coolant introduced into the annular water-cooled cavity (4-2) can be deionized water or ethylene glycol aqueous solution, and is forcibly circulated by an external circulating cooling unit to protect the sealing elements from high temperature damage.

[0021] Preferably, at least one static sealing ring is provided between the movable sealing unit (4) and the inner wall of the sealing tube (2) to achieve static sealing between the two; further, there are two static sealing rings, namely a first sealing ring (4-3) and a second sealing ring (4-4). The static sealing ring is preferably an O-ring, and its material can be selected from fluororubber, silicone rubber or perfluoroether rubber according to the working temperature.

[0022] Secondly, it also includes an operating method for the aforementioned integrated furnace.

[0023] An operating method for an integrated sintering furnace for 3D printing ceramics includes the following steps:

[0024] S1: Loading: Control the lifting drive mechanism (3) to drive the sealing assembly to descend to the second position and load the ceramic blank onto the sintering platform (6);

[0025] S2: Formation of a sealed space: Control the lifting drive mechanism (3) to drive the sealing assembly to rise to the first position, so that the sealing tube (2) cooperates with the furnace body (1) to form a sealed space around the ceramic blank;

[0026] S3: Atmosphere Replacement: Process gas is introduced into the sealed space through the atmosphere supply pipeline (7), and the sealed space is evacuated through the exhaust channel of the movable sealing unit (4). This process is repeated at least once to replace and remove the air in the sealed space. The process gas can be nitrogen, argon, or a mixture thereof. This step is completed automatically by controlling the start and stop of the solenoid valve and the vacuum pump through a program.

[0027] S4: Adhesive Discharge: The heating element of the furnace body (1) is heated to a adhesive discharge temperature and kept at that temperature. Simultaneously, process gas is continuously introduced into the sealed space through the atmosphere supply pipeline (7) to decompose the organic binder in the ceramic blank and discharge it with the airflow. The adhesive discharge temperature is usually between 300°C and 600°C, determined experimentally based on the binder composition. The decomposed organic vapor is guided to an external condenser or incinerator for treatment through the second exhaust port (4-7).

[0028] S5: Carbon removal: Stop the process gas supply, control the lifting drive mechanism (3) to drive the sealing component to descend to the second position, so that the sealed space is connected with the outside air, and heat preservation is carried out in the air atmosphere to oxidize and remove the residual carbon in the ceramic blank. This step uses the lifting of the sealing component to realize the rapid and automatic switching of the atmosphere from inert to air.

[0029] S6: Sintering: Control the lifting drive mechanism (3) to drive the sealing assembly to rise again to the first position to re-form the sealed space, introduce process gas into it through the atmosphere supply pipeline (7), and control the heating element to heat up to a sintering temperature for heat preservation, so that the ceramic blank is densified. The sintering temperature depends on the type of ceramic material, for example, zirconium oxide is about 1450-1550℃, and alumina is about 1600-1800℃.

[0030] S7: Cooling: After sintering, under the condition of continuous process gas supply, the heating element is controlled to cool down to room temperature according to a preset cooling program. The preset cooling program can be furnace cooling or program-controlled cooling to prevent ceramic products from cracking due to thermal stress.

[0031] Compared with existing technologies, this invention utilizes a liftable dynamic sealing component to continuously complete the entire process of glue removal and sintering within the same equipment, fundamentally avoiding damage caused by the transfer of brittle green blanks and significantly improving the yield. By eliminating intermediate steps through "one-stop" processing, it greatly shortens the production cycle, reduces equipment investment and energy consumption, improves production efficiency, and lowers overall costs. Relying on fully automated control to eliminate human intervention variables, it ensures precise and stable process parameters and guarantees highly consistent product performance. The innovative use of a lifting sealing component enables rapid and automatic switching of the atmosphere environment at different process stages, demonstrating flexible and precise process control capabilities. This successfully solves the core problems of low yield, poor efficiency, high cost, and difficulty in ensuring consistency in the post-processing of ceramic 3D printing. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 The structure of the integrated sintering furnace for 3D printing ceramic molding described in this utility model. Figure 1 .

[0034] Figure 2 The structure of the integrated sintering furnace for 3D printing ceramic molding described in this utility model. Figure 2 .

[0035] Figure 3 This is a cross-sectional view of the integrated furnace for sintering and debinding ceramics used in 3D printing, as described in this utility model.

[0036] Figure 4 This is a structural diagram of the combination of the lifting drive mechanism and the sealing component of this utility model.

[0037] Figure 5 This is a cross-sectional view of the combined structure of the lifting drive mechanism and sealing component described in this utility model.

[0038] Figure 6 This is a top view of the combined structure of the lifting drive mechanism and sealing component described in this utility model.

[0039] Figure 7 This is a structural diagram of the movable sealing unit described in this utility model.

[0040] Figure 8 This is a cross-sectional view of the movable sealing unit described in this utility model.

[0041] Figure 9 This is a top view of the movable sealing unit described in this utility model.

[0042] Figure Labels

[0043] 1. Furnace body, 2. Sealing pipe, 3. Lifting drive mechanism, 4. Moving sealing unit, 5. Support structure, 6. Sintering platform, 7. Atmosphere supply pipeline, 8. Control unit, 9. Power management module, 10. Human-machine interface.

[0044] 1-1. Thermal insulation lining; 1-2. Heating element; 1-3. Electrical connection terminal; 1-4. Annular sealing structure; 1-5. External load-bearing frame.

[0045] 3-1. Fixed base; 3-2. Moving platform; 3-3. Drive motor; 3-4. Lead screw; 3-5. Lead screw nut; 3-6. Lead screw seat; 3-7. Guide shaft.

[0046] 4-1. Exhaust chamber; 4-2. Annular water-cooled chamber; 4-3. First sealing ring; 4-4. Second sealing ring; 4-5. Flange; 4-6. Dynamic seal; 4-7. Second exhaust port; 4-11. Gas through hole; 4-12. First exhaust port; 4-21. Coolant circulation port; 4-61. Sealing ring inflation port. Detailed Implementation

[0047] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0048] It should be noted that similar labels in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0049] It should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0050] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0051] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0052] Specifically, in this invention, radial direction refers to the radial direction passing through the center of the circle (or the center of the rotation axis), which is a straight line direction from the center to the edge or from the edge to the center. Axial direction refers to the direction along the rotation axis (or central axis) of the object, which is a straight line direction parallel to the rotation axis.

[0053] Example 1:

[0054] like Figures 1 to 3 As shown, this embodiment provides an integrated furnace for sintering and debinding ceramics for 3D printing.

[0055] The core structure of the integrated furnace includes a furnace body 1, a support structure 5, a lifting drive mechanism 3, a sealing component, and an atmosphere supply pipeline 7.

[0056] The furnace body 1 adopts a cylindrical structure with a circular opening at the center of its bottom. From the outside to the inside, the wall of the furnace body 1 consists of a steel outer shell, a heat-insulating lining 1-1, and heating elements 1-2. The heat-insulating lining 1-1 is made of lightweight refractory material using alumina hollow spherical bricks, with a thickness of 200mm, effectively reducing heat loss. The heating elements 1-2 are U-shaped silicon molybdenum rods, arranged in six groups, evenly distributed on the inner wall of the furnace body 1, forming a symmetrical heating layout. The top of the furnace body 1 is equipped with electrical connection terminals 1-3, employing a water-cooled electrode structure, connected to the high-voltage output terminal of the power management module 9 via a high-temperature resistant cable.

[0057] The support structure 5 consists of a corundum column, vertically positioned directly below the furnace body 1. A sintering platform 6 is supported at the top. The sintering platform 6 extends into the furnace body 1 through an opening at the bottom of the support structure 5. The bottom of the support structure 5 is fixed to the fixed base 3-1 of the lifting drive mechanism 3 via a flange connection.

[0058] like Figures 4 to 6 As shown, the lifting drive mechanism 3 includes a fixed base 3-1, a moving platform 3-2, a drive motor 3-3, and a transmission assembly. The drive motor 3-3 is a servo motor, which is fixed to the fixed base 3-1 via a motor mount.

[0059] The transmission assembly employs a precision ball screw and nut pair, including a screw 3-4, a nut 3-5, and a screw seat 3-6. The upper end of the screw 3-4 is supported by the screw seat 3-6, and the lower end is connected to the output end of the drive motor 3-3. Four sets of guide shafts 3-7 are respectively located at the four corners of the fixed base 3-1. The movable platform 3-2 has a nut 3-5 fixedly installed on its side, and linear bearings are installed at its four corners, which respectively cooperate with the four guide shafts 3-7. This layout allows the support structure 5 to pass through the middle of the movable platform 3-2 and, in horizontal projection, to be located within the space enclosed by the transmission assembly and the guide assembly.

[0060] The sealing assembly is mounted on the moving platform 3-2 and includes a moving sealing unit 4 and a sealing tube 2. The sealing tube 2 is a cylindrical structure with a 45° conical surface machined on its upper edge. When the lifting drive mechanism 3 drives the sealing assembly to rise to the first position, the conical surface presses against the annular sealing structure 1-4 provided on the inner top wall of the furnace body 1. The annular sealing structure 1-4 is a flexible graphite sealing ring embedded in the groove of the furnace body top wall, which undergoes elastic deformation under the positive pressure of the sealing tube 2 to achieve a tight seal.

[0061] like Figures 7 to 9 As shown, the movable sealing unit 4 is a multi-layer composite structure, which includes, from bottom to top, a dynamic sealing element 4-6, an annular exhaust chamber 4-1, and an annular water-cooling chamber 4-2.

[0062] The dynamic sealing element 4-6 is an inflatable sealing ring with a sealing lip on its inner ring side. When the sealing assembly rises to the first position to form a sealed space, compressed air of 0.4-0.6 MPa is introduced into the inflatable sealing ring through the sealing ring inflation port 4-61, causing it to expand radially and clamp the support structure 5, thus achieving a movable seal.

[0063] The annular exhaust chamber 4-1 is a welded metal structure with 10 evenly distributed gas through holes 4-11, each 15mm in diameter, on its top, communicating with a sealed space. The sidewall of the exhaust chamber 4-1 is provided with a first exhaust port 4-12 and a second exhaust port 4-7. The first exhaust port 4-12 is connected to an external vacuum pump unit via a vacuum bellows, and the second exhaust port 4-7 is connected to external exhaust gas treatment equipment via a pipe.

[0064] The annular water-cooled cavity 4-2 is located above the annular exhaust cavity 4-1 and is a sealed cavity formed by welding two layers of stainless steel plates. Its side wall is provided with a coolant circulation port 4-21, which is connected to an external circulating cooling unit through a hose to allow 25°C deionized water to be introduced for forced circulation cooling, ensuring that the operating temperature of the movable sealing unit 4 does not exceed 60°C.

[0065] The top of the movable sealing unit 4 is a flange 4-5, which is fixedly connected to the movable platform 3-2 by bolts. Two static sealing rings are provided between the movable sealing unit 4 and the inner wall of the sealing pipe 2: a first sealing ring 4-3 and a second sealing ring 4-4. The static sealing rings are made of fluororubber O-rings, with a temperature resistance of 200℃.

[0066] The atmosphere supply pipeline 7 is made of 316L stainless steel, and its outlet enters from the top wall of the furnace body 1, located in the sealed space formed after the sealing pipe 2 rises. The inlet is connected to the process gas source through a mass flow meter.

[0067] The control unit 8 is a PLC controller, connected via control cables to the drive motor 3-3, the solenoid valve of the atmosphere supply pipeline 7, the vacuum pump assembly, and the heating element 1-2. The power management module 9 uses a multi-output switching power supply, providing 380V AC output for the heating element 1-2 and 24V DC output for the control unit 8 and drive motor 3-3. The human-machine interface 10 is a 10-inch touchscreen, communicating with the control unit 8 via Ethernet, used for setting process parameters and displaying equipment operating status.

[0068] like Figure 1 As shown, an external load-bearing frame 1-5 is also provided outside the furnace body 1. The frame is a steel column structure, with its bottom end connected to the top of the furnace body 1 via a flange, and its top end fixed to the external fixed foundation via expansion bolts. When the sealing pipe 2 rises and presses against the furnace body 1 to seal, the force generated by the sealing assembly is directly transmitted to the external fixed foundation through the external load-bearing frame 1-5, preventing the force from acting on the heat insulation lining 1-1.

[0069] This embodiment achieves the integrated debinding and sintering function through the above-described specific structure. The ceramic green body is always placed on the sintering platform 6 throughout the entire process, completely avoiding the damage problem caused by the transfer of brittle green body in the prior art.

[0070] Example 2:

[0071] This embodiment describes the control system configuration and process parameter integration scheme of the integrated furnace based on Embodiment 1.

[0072] like Figure 1-3 As shown, the control unit 8 uses an industrial-grade PLC as the main controller, equipped with analog input / output modules and digital input / output modules. The PLC communicates with the servo driver of the drive motor 3-3 via a PROFINET bus, controlling the lifting position accuracy of the sealing assembly to ±0.1mm. Specifically, a limit sensor is set at the first position to ensure that the pressing force between the sealing tube 2 and the annular sealing structure 1-4 is controlled within the range of 2-5kN; a photoelectric sensor is set at the second position to ensure that the sintering platform 6 is fully exposed for easy loading.

[0073] The control unit 8 controls the mass flow meter on the atmosphere supply pipeline 7 via a 4-20mA analog signal to achieve precise proportioning and flow control of process gases such as nitrogen and argon, with a control accuracy of ±1%FS. Simultaneously, it communicates with a vacuum gauge via an RS485 interface to monitor the vacuum level of the confined space in real time, with a control range of 10... 5 Pa to 10⁻¹Pa.

[0074] The power management module 9 specifically adopts a combination of a three-phase isolation transformer (380V / 220V, capacity 30kVA) and a high-frequency switching power supply (output: 24VDC / 10A). The three-phase isolation transformer provides a stable high-voltage power supply for the heating elements 1-2, while also providing electrical isolation; the high-frequency switching power supply powers low-power devices such as the PLC, sensors, and solenoid valves.

[0075] The human-machine interface 10 is specifically a 10-inch industrial touchscreen with a built-in process formula management system. Operators can select pre-stored process formulas, such as "zirconia debinding sintering process", and the system will automatically call up the corresponding temperature curve and atmosphere control program.

[0076] Example 3:

[0077] This embodiment provides several alternative transmission schemes for the lifting drive mechanism 3.

[0078] In one embodiment, the transmission assembly employs a rack and pinion mechanism. Specifically, precision racks (module 2, accuracy grade 6) are machined on two of the four guide shafts 3-7, and two servo geared motors (reduction ratio 10:1) are correspondingly installed on the moving platform 3-2. The gears on the motor output shafts mesh with the racks. Through synchronous control of the dual motors, the moving platform 3-2 achieves smooth lifting and lowering, with a maximum load capacity of 1000 kg.

[0079] In another embodiment, the transmission assembly employs a hydraulic drive system. It includes a hydraulic power unit (motor power 5.5kW, rated pressure 21MPa), a double-acting hydraulic cylinder (cylinder diameter 80mm, rod diameter 45mm, stroke 800mm), and a servo proportional valve. The cylinder body is fixed to the fixed base 3-1, and the top of the piston rod is connected to the moving platform 3-2. By controlling the opening size and direction of the servo proportional valve, precise speed and position control of the moving platform 3-2 is achieved, with a position repeatability accuracy of ±0.2mm.

[0080] In another embodiment, the transmission assembly employs a synchronous belt drive mechanism. Four sets of synchronous belt drive units are arranged between the fixed base 3-1 and the top frame. The synchronous belt is a polyurethane steel core belt (50mm wide), and the moving platform 3-2 is connected to the synchronous belt via clamps. The drive motor 3-3 drives the synchronous belt through a synchronous belt pulley reduction mechanism (reduction ratio 5:1), thereby achieving the lifting and lowering of the moving platform 3-2.

[0081] Example 4:

[0082] This embodiment focuses on the operation method, detailing how to utilize the integrated furnace to achieve integrated processing of ceramic blanks. This embodiment uses zirconia ceramic blanks as the processing object.

[0083] S1: Loading Preparation

[0084] Control the lifting drive mechanism (3) to drive the sealing assembly down to the second position, so that the sintering platform (6) is fully exposed; use a special clamp to accurately place the ceramic blank on the sintering platform (6) to ensure that the offset between the center of the blank and the center of the platform is <1mm; select the "zirconia precision parts" process formula through the human-machine interface (10), and the system will automatically load the corresponding parameters.

[0085] S2: Formation of a closed space

[0086] Start the drive motor (3-3) and lift the sealing assembly to the first position at a speed of 5 mm / s; the position sensor provides real-time feedback to ensure that the pressure between the top of the sealing tube (2) and the annular sealing structure (1-4) is stable at 3.5 ± 0.5 kN; inject 0.5 MPa nitrogen into the gas-filled sealing ring (4-6) through the gas-filled sealing ring inlet (4-61) to achieve dynamic sealing with the support structure (5).

[0087] S3: Atmosphere Replacement

[0088] Turn on the vacuum pump and evacuate the sealed space to 10Pa through the first exhaust port (4-12); fill the sealed space with high-purity nitrogen to atmospheric pressure through the atmosphere supply pipeline (7), and repeat this process 3 times; finally, maintain the sealed space at a negative pressure of 10000Pa and the oxygen content <10ppm.

[0089] S4: Programmed glue removal

[0090] Perform the following temperature-atmosphere program: room temperature → 300℃: heating rate 1℃ / min, nitrogen flow rate 15L / min; hold at 300℃ for 120min: nitrogen flow rate 20L / min, introduce the decomposed organic matter into the absorption device through the second exhaust port (4-7); 300℃ → 500℃: heating rate 0.5℃ / min, nitrogen flow rate 15L / min; hold at 500℃ for 180min: nitrogen flow rate 10L / min.

[0091] Throughout the glue removal stage, 25°C deionized water is continuously introduced through the cooling channel of the moving sealing unit (4) to ensure that the temperature of the sealing system is <60°C.

[0092] S5: Atmosphere switching carbon emission

[0093] Stop the nitrogen supply and control the lifting drive mechanism (3) to lower the sealing component to the second position at a speed of 2 mm / s; connect the sealed space with the clean room environment and use oxygen in the air to remove carbon; keep warm at 500℃ for 120 min.

[0094] S6: Densification sintering

[0095] Argon gas is introduced into the atmosphere supply pipeline (7) to a slightly positive pressure, and the sintering process is performed: 500℃→1200℃: heating rate 3℃ / min, argon gas flow rate 8L / min; 1200℃ holding for 60min: eliminating temperature gradient; 1200℃→1500℃: heating rate 2℃ / min, argon gas flow rate 5L / min; 1500℃ holding for 240min: achieving complete densification.

[0096] S7: Controllable Cooling

[0097] Stop heating and control the temperature drop according to the preset program: 1500℃→1000℃: cooling rate 2℃ / min, argon flow rate 8L / min; 1000℃→600℃: cooling rate 3℃ / min, argon flow rate 10L / min; 600℃→room temperature: cooling with the furnace, argon flow rate 5L / min. When the furnace temperature drops below 80℃, open the sealing assembly and remove the finished product.

[0098] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A sintering furnace for 3D printing ceramics, characterized in that, include: The furnace body (1) has an opening at its bottom; A support structure (5) is provided below the furnace body (1) for supporting the sintering platform (6) of the ceramic blank. The platform (6) extends into the furnace body (1) through the opening via the support structure (5). A lifting drive mechanism (3) is located below the furnace body (1); A sealing assembly is connected to the lifting action part of the lifting drive mechanism (3) and can be driven to move vertically along the support structure (5); the sealing assembly includes a movable sealing unit (4) and a sealing tube (2) disposed thereon; wherein, the sealing assembly is configured such that when it rises to the first position, the sealing tube (2) cooperates with the inner wall of the furnace body (1) to form a sealed space around the sintering platform (6) inside the furnace body (1); An atmosphere supply pipeline (7) has its outlet connected to the sealed space for filling the sealed space with process gas.

2. The integrated furnace for sintering and debinding ceramics for 3D printing as described in claim 1, characterized in that: The sealing assembly can be driven down to a second position by the lifting drive mechanism (3), in which the sealing tube (2) is completely detached from the furnace body (1) and the space above the sintering platform (6) is completely open.

3. The integrated furnace for sintering and debinding ceramics for 3D printing as described in claim 2, characterized in that: It also includes a control unit (8) and a power management module (9). The control unit (8) is electrically connected to the lifting drive mechanism (3) and the atmosphere supply pipeline (7), and is configured to control the movement of the sealing assembly between the first position and the second position, and control the process gas to be introduced into the sealed space according to a preset program; The power management module (9) is connected to the control unit (8) and is configured to provide at least two different output voltages, including a high voltage output for powering the heating elements inside the furnace body (1) and at least one conventional voltage output for powering the control unit (8) and the lifting drive mechanism (3).

4. The integrated furnace for sintering and debinding ceramics for 3D printing as described in claim 3, characterized in that: It also includes a human-machine interface (10), which is communicatively connected to the control unit (8) and is used to receive process parameter instructions input by the user and display the operating status information of the integrated furnace.

5. The integrated furnace for sintering and debinding ceramics for 3D printing as described in claim 3, characterized in that: The furnace body (1) includes a heat-insulating lining (1-1), a heating element (1-2) disposed inside the furnace body (1) and surrounding the periphery of the sealed space, and an electrical connection terminal (1-3) disposed on the upper part of the furnace body (1); the electrical connection terminal (1-3) is electrically connected to the heating element (1-2) and electrically connected to the high voltage output of the power management module (9).

6. The integrated furnace for sintering and debinding ceramics for 3D printing as described in claim 5, characterized in that: The furnace body (1) has an annular sealing structure (1-4) on its inner top wall. When the sealing tube (2) rises to the first position, its top end is pressed against the annular sealing structure (1-4) to form the top sealing interface of the sealed space.

7. The integrated furnace for sintering and debinding ceramics for 3D printing as described in claim 5, characterized in that: It also includes an external load-bearing frame (1-5), which is disposed outside the furnace body (1), with its bottom end connected to the top structure of the furnace body (1) and its top end connected to an external fixed foundation; the external load-bearing frame (1-5) is configured to bear and transmit the force generated by the sealing assembly when the sealing tube (2) rises and presses against the furnace body (1) for sealing, thereby preventing the force from acting directly on the heat insulation lining (1-1) and its associated structure.

8. The integrated furnace for sintering and debinding ceramics for 3D printing as described in claim 1, characterized in that: The lifting drive mechanism (3) includes a fixed base (3-1), a moving platform (3-2), a drive motor (3-3), and a transmission assembly; The drive motor (3-3) is fixed on the fixed base (3-1); The transmission assembly is connected between the output end of the drive motor (3-3) and the moving platform (3-2), and is configured to convert the rotational motion of the drive motor (3-3) into linear motion of the moving platform (3-2) in the vertical direction; The sealing assembly is mounted on the mobile platform (3-2) and can move synchronously with it.

9. The integrated furnace for sintering and debinding ceramics for 3D printing as described in claim 1, characterized in that: The movable sealing unit (4) integrates a sealing tube mounting part, an exhaust channel, a cooling channel and at least one dynamic sealing element (4-6). The sealing tube (2) is installed in the sealing tube mounting part; The exhaust passage is configured to communicate with the sealed space and is provided with a first exhaust port (4-12) for connecting to an external vacuum device and a second exhaust port (4-7) for connecting to an external exhaust gas treatment device. The cooling channel is arranged around the outer periphery of the exhaust channel; the dynamic seal (4-6) is arranged on the inner ring side of the movable sealing unit (4) and is configured to be activated when the sealed space is formed, so as to achieve a movable seal between the movable sealing unit (4) and the support structure (5).

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