A laboratory box-type resistance furnace

Abstract

The utility model discloses a laboratory box type resistance furnace relates to resistance furnace technical field, including furnace body, the movable material tray is equipped in furnace body, and two pieces of baffle are inserted along the length direction of furnace body, and the lifting mechanism is connected to the baffle upper end, when the baffle drops and seals, the furnace body is divided into heating cavity, transition chamber, cooling chamber, and the furnace door is hinged to the same side of heating cavity and cooling chamber, and the control mechanism of integrated touch screen, PLC controller, temperature acquisition module is equipped below furnace body, and the silicon molybdenum rod heating body is equipped in heating cavity, and the silicon carbon rod heating body is equipped in transition chamber, and the adjustable speed exhaust fan and HEPA filter screen are equipped in cooling chamber, the material tray is driven through the screw rod and asynchronous motor, and slides along the ceramic guide rail. Solve the problem that the low toughness ceramic high temperature sensitive section cooling exceeds the safe range caused by the passive heat dissipation of conventional single hearth furnace, realize accurate temperature control and efficient cooling, and adapt to the laboratory research and development demand.

Description

Technical Field

[0001] This utility model relates to the field of resistance furnace technology, and in particular to a box-type resistance furnace for laboratory use. Background Technology

[0002] In ceramic manufacturing, the sintering process requires high temperatures to densify the green body, while the subsequent cooling stage has a crucial impact on the final properties and yield of the ceramic. Improper control of the cooling rate can lead to thermal stress within the ceramic, especially for low-toughness ceramics such as silicon nitride and beryllium oxide. These ceramics have inherently low fracture toughness, and their tolerance threshold to thermal stress is much lower than that of ordinary ceramics. During the cooling process, thermal stress accumulation can easily lead to through-cracks or internal microcracks, which restricts the laboratory research and small-batch production of low-toughness ceramic materials.

[0003] Currently, in most laboratories, conventionally configured single-furnace box-type resistance furnaces are the mainstream equipment for sintering low-toughness ceramics. Their cooling method mainly relies on natural convection of residual heat in the furnace, without an active cooling system. This presents technical limitations such as uncontrollable cooling rate and high risk in the high-temperature sensitive range. During the cooling process after the low-toughness ceramics are sintered, they need to pass through a "high-temperature sensitive range" of 1700-800℃. In this range, the coefficient of thermal expansion of low-toughness ceramics changes significantly, and the material has poor plasticity and weak stress release ability. The safe cooling rate needs to be strictly controlled at 3-8℃ / min. However, when using a conventional single-furnace box-type resistance furnace for passive heat dissipation, the measured cooling rate in this high-temperature range can reach 10-15℃ / min under normal laboratory conditions, which far exceeds the thermal stress tolerance range of low-toughness ceramics. When the temperature drops to the low-temperature range below 800℃, the heat loss is hindered by the thermal resistance of the furnace insulation layer, and the cooling rate often drops to 2-3℃ / min, forming a cooling curve of "faster cooling in the high-temperature sensitive range and slower cooling in the low-temperature range". This further aggravates the accumulation of thermal stress inside the low-toughness ceramic, leading to a continuous increase in the risk of cracking. Utility Model Content

[0004] To address the aforementioned problems, the purpose of this invention is to provide a laboratory box-type resistance furnace that solves the problem that conventional single-furnace box-type resistance furnaces rely on passive natural heat dissipation, which leads to the temperature drop rate of the high-temperature sensitive section after sintering of low-toughness ceramics exceeding the safe control range, thereby causing the accumulation of internal thermal stress and the generation of cracks in the ceramics.

[0005] The technical solution of this utility model is as follows: A laboratory box-type resistance furnace includes a furnace body with a material tray slidably disposed within its length. Two baffle plates are spaced apart along the length of the furnace body, with the upper ends of both baffle plates extending outside the furnace body. Each baffle plate has a corresponding lifting mechanism at its upper end, which drives the baffle plate to move up and down along the height of the furnace body. When both baffle plates descend to a point where their lower ends are sealed against the bottom of the furnace body, the internal space of the furnace body is divided from right to left into a heating chamber for sintering heating of workpieces, a transition chamber for cooling buffering of workpieces, and a cooling chamber for active cooling of workpieces. Furnace doors are hinged to the heating chamber and cooling chamber on the same side of the furnace body. A control mechanism is located below the furnace body, integrating a touch screen operation panel, a PLC controller, and a temperature acquisition module.

[0006] Furthermore, the bottom of the furnace body has three parallel grooves, all of which are arranged along the length of the furnace body, penetrating the heating chamber, transition chamber, and cooling chamber; ceramic guide rails are provided in the grooves on both sides, and a lead screw is rotatably installed in the middle groove; the lower end of the material tray is provided with a ceramic slider that is slidably adapted to the ceramic guide rail, and a lead screw nut that is threadedly adapted to the lead screw; one end of the lead screw is rotatably connected to the inner wall of the middle groove, and the other end extends out of the furnace body and is connected to the output shaft of the asynchronous motor through a coupling.

[0007] Furthermore, the lower end face of each barrier plate is integrally extended with a sealing baffle that extends into the groove. The sealing baffle is provided with a through groove that adapts to the contour of the ceramic guide rail and avoids the lead screw, so as to reduce the airflow between adjacent chambers in the closed state.

[0008] Furthermore, each lifting mechanism includes two guide rods arranged parallel to each other along the height of the furnace body. The two guide rods are respectively inserted into guide holes near the two ends of the corresponding baffle plates, and the baffle plates and guide rods are slidably engaged. The lower ends of the two guide rods extend to the bottom of the furnace body and are fixedly connected to the bottom of the furnace body. The upper ends extend upwards out of the baffle plates and are connected to an inverted U-shaped mounting plate. The mounting plate spans above the baffle plates and its two ends are connected to the upper end face of the furnace body. A cylinder is provided in the middle of the horizontal section of the mounting plate. The output shaft of the cylinder passes downwards through the mounting plate and is connected to the upper end face of the corresponding baffle plate.

[0009] Furthermore, the output shaft of the cylinder is connected to the upper end face of the corresponding baffle plate through a cylinder universal floating joint. The cylinder universal floating joint is used to compensate for the slight offset during the lifting and lowering process of the baffle plate, ensuring that the baffle plate is lifted and lowered vertically and smoothly along the guide rod.

[0010] Furthermore, a first heating assembly is fixedly installed on the top wall, the right side wall away from the baffle plate, and the rear side wall away from the furnace door within the heating chamber. The first heating assembly includes silicon molybdenum rod heating elements with a rated operating temperature of not less than 1800℃. The silicon molybdenum rod heating elements on the top wall are evenly spaced along the width direction of the furnace body, the silicon molybdenum rod heating elements on the right side wall are equidistantly spaced along the height direction of the furnace body, and the silicon molybdenum rod heating elements on the rear side wall are equidistantly spaced along the length direction of the furnace body. The power of all silicon molybdenum rod heating elements is independently controllable.

[0011] Furthermore, the front sidewall, rear sidewall, and top wall of the transition cavity are all fixedly provided with a second heating assembly. The second heating assembly includes silicon carbide rod heating elements with a rated operating temperature adapted to the cooling buffer zone of 800-1700℃. The silicon carbide rod heating elements on the front and rear sidewalls are arranged at equal intervals along the height direction of the furnace body, and the silicon carbide rod heating elements on the top wall are evenly spaced along the width direction of the furnace body. The power of all silicon carbide rod heating elements is independently controllable to adjust the temperature of the transition cavity.

[0012] Furthermore, the cooling chamber has an air inlet hole at the top and an air outlet hole on the side wall. An adjustable air intake fan is installed on the outside of the furnace body corresponding to the air inlet hole, and an adjustable exhaust fan is installed on the outside of the furnace body corresponding to the air outlet hole.

[0013] Furthermore, the intake fan is connected to the upper surface of the furnace body via a detachable filter element mounting base. A HEPA filter with a filtration accuracy of not less than 0.3μm is snapped into the filter element mounting base. The HEPA filter is used to filter air impurities entering the cooling chamber.

[0014] Furthermore, all the barrier plates are made of high-temperature resistant ceramic substrates, and the surface of the barrier plate facing the heating cavity is covered with a high-alumina ceramic reflective layer, which is used to compensate for the heat radiation loss of the missing left side wall of the heating cavity.

[0015] Furthermore, the outer wall of the furnace body's cooling chamber, away from the transition chamber (i.e. away from the baffle plate), adopts a bolt-detachable connection structure, and a high-temperature resistant sealing strip is provided at the joint between the side wall and the furnace body frame; this facilitates inspection and maintenance as well as assembly.

[0016] The beneficial effects of this utility model are as follows: 1. This utility model achieves active control over the entire cooling process of low-toughness ceramics after sintering through a segmented structural design of three cavities: heating cavity, transition cavity, and cooling cavity. It specifically optimizes the limitations of "passive heat dissipation in a single cavity" in conventional single-furnace furnaces: the heating cavity can stably provide the environment required for high-temperature sintering; the transition cavity controls the cooling rate of the high-temperature sensitive section, which helps reduce the risk of ceramics cracking due to thermal stress; and the cooling cavity accelerates the cooling speed of the low-temperature section through an adjustable-speed fan, improving the problem of insufficient cooling efficiency in the low-temperature section of conventional furnaces. The three cavities form a complete temperature control link of "sintering-buffered cooling-rapid cooling", effectively improving the dual problems of "high-temperature section cooling rate exceeding the safe range and low-temperature section cooling being slow" in conventional furnaces.

[0017] 2. This utility model ensures operational reliability and sample safety through multiple detailed designs: the sealing baffle at the lower end of the barrier plate is adapted to the groove at the bottom of the furnace body, which can reduce airflow between adjacent chambers and ensure stable temperature field of each chamber; the HEPA filter of the cooling chamber can filter air impurities entering the chamber and avoid sample contamination; the material tray adopts ceramic guide rail and lead screw drive to achieve smooth sliding in high temperature environment and reduce vibration damage to low toughness ceramics; the universal floating joint of the cylinder can compensate for the slight offset during the lifting and lowering of the barrier plate, ensuring smooth lifting and lowering of the barrier plate and reliable sealing of the chamber, which meets the laboratory's requirements for high precision and high stability of the equipment in many aspects. Attached Figure Description

[0018] Figure 1 This is a front view structural diagram of the present invention.

[0019] Figure 2 This is a schematic diagram of the rear view structure of this utility model.

[0020] Figure 3 This is a cross-sectional view of the present invention (without furnace door).

[0021] Figure 4 This is a schematic diagram of one set of control mechanisms and barrier plates of this utility model.

[0022] Figure 5 This is a disassembly diagram of the intake fan, filter element mounting base, and filter screen of this utility model.

[0023] Reference numerals in the attached drawings: 1. Furnace body; 1-1. Heating chamber; 1-1.1. First heating component; 1-2. Transition chamber; 1-2.1. Second heating component; 1-3. Cooling chamber; 1-3.1. Inlet fan; 1-3.2. Exhaust fan; 1-3.2.1. Filter element mounting base; 1-3.2.1.1. Filter screen; 1-4. Groove; 1-5. Ceramic guide rail; 1-6. Lead screw; 1-7. Asynchronous motor; 2. Material tray; 3. Baffle plate; 3-1. Sealing baffle; 4. Lifting mechanism; 4-1. Guide rod; 4-2. Mounting plate; 4-3. Cylinder; 4-4. Cylinder universal floating joint; 5. Furnace door. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0025] like Figures 1 to 5 As shown, the furnace includes a furnace body 1, with a material tray 2 slidably disposed inside the furnace body 1 along its length. Two baffle plates 3 are inserted at intervals along the length of the furnace body 1, with the upper ends of the baffle plates 3 extending outside the furnace body 1. Each baffle plate 3 has a corresponding lifting mechanism 4 at its upper end, which drives the baffle plate 3 to rise and fall along the height of the furnace body 1. When both baffle plates 3 descend to their lower end faces and seal against the bottom of the furnace body 1, the internal space of the furnace body 1 is divided from right to left into a heating chamber 1-1 for sintering heating of the workpiece, a transition chamber 1-2 for cooling buffering of the workpiece, and a cooling chamber 1-3 for active cooling of the workpiece. Furnace doors 5 are hinged to the heating chamber 1-1 and the cooling chamber 1-3 on the same side of the furnace body 1. A control mechanism is provided below the furnace body 1, which integrates a touch screen operation panel, a PLC controller, and a temperature acquisition module.

[0026] Furthermore, three parallel grooves 1-4 are provided at the bottom of the furnace body 1. The three grooves 1-4 are arranged to pass through the heating chamber 1-1, the transition chamber 1-2 and the cooling chamber 1-3 along the length of the furnace body 1. Ceramic guide rails 1-5 are provided in the grooves 1-4 on both sides, and a lead screw 1-6 is rotatably installed in the middle groove 1-4. The lower end of the material tray 2 is provided with a ceramic slider that is slidably adapted to the ceramic guide rail 1-5, and a silicon nitride lead screw nut that is threadedly adapted to the silicon nitride lead screw 1-6. One end of the lead screw 1-6 is rotatably connected to the inner wall of the middle groove 1-4, and the other end extends out of the furnace body 1 and is connected to the output shaft of the asynchronous motor 1-7 through a coupling.

[0027] Furthermore, the lower end face of the barrier plate 3 is integrally extended with a sealing baffle 3-1 that extends into the groove 1-4. The sealing baffle 3-1 is provided with a contour that adapts to the ceramic guide rail 1-5 and a through groove that avoids the lead screw 1-6, so as to reduce the airflow between adjacent chambers in the closed state.

[0028] Furthermore, each lifting mechanism 4 includes two guide rods 4-1 arranged parallel to each other along the height direction of the furnace body 1. The two guide rods 4-1 are respectively inserted into the guide holes near the two ends of the corresponding baffle plate 3, and the baffle plate 3 and the guide rods 4-1 are slidably engaged. The lower ends of the two guide rods 4-1 extend to the bottom of the furnace body 1 and are fixedly connected to the bottom of the furnace body 1. The upper ends extend upwards out of the baffle plate 3 and are connected to an inverted U-shaped mounting plate 4-2. The mounting plate 4-2 spans above the baffle plate 3 and its two ends are connected to the upper end face of the furnace body 1. A cylinder 4-3 is provided in the middle of the horizontal section of the mounting plate 4-2. The output shaft of the cylinder 4-3 passes downwards through the mounting plate 4-2 and is connected to the upper end face of the corresponding baffle plate 3.

[0029] Furthermore, the output shaft of cylinder 4-3 is connected to the upper end face of the corresponding baffle plate 3 through cylinder universal floating joint 4-4. Cylinder universal floating joint 4-4 is used to compensate for the slight offset during the lifting and lowering process of baffle plate 3, ensuring that baffle plate 3 is vertically and smoothly lifted and lowered along guide rod 4-1.

[0030] Furthermore, the top wall, the right side wall away from the baffle plate 3, and the rear side wall away from the furnace door 5 of the heating chamber 1-1 are all fixedly provided with a first heating assembly 1-1.1. The first heating assembly 1-1.1 includes silicon molybdenum rod heating elements with a rated operating temperature of not less than 1800℃. Among them, the silicon molybdenum rod heating elements on the top wall are evenly spaced along the width direction of the furnace body 1, the silicon molybdenum rod heating elements on the right side wall are equidistantly spaced along the height direction of the furnace body 1, and the silicon molybdenum rod heating elements on the rear side wall are equidistantly spaced along the length direction of the furnace body 1. The power of all silicon molybdenum rod heating elements is independently controllable.

[0031] Furthermore, the front, rear, and top walls of the transition cavity 1-2 are all fixedly equipped with a second heating assembly 1-2.1. The second heating assembly 1-2.1 includes silicon carbide heating elements with a rated operating temperature adapted to the cooling buffer zone of 800-1700℃. The silicon carbide heating elements on the front and rear walls are arranged at equal intervals along the height direction of the furnace body 1, and the silicon carbide heating elements on the top wall are evenly spaced along the width direction of the furnace body 1. The power of all silicon carbide heating elements is independently controllable to adjust the temperature of the transition cavity 1-2.

[0032] Furthermore, the top of the cooling chamber 1-3 is provided with an air inlet hole, and the side wall of the chamber is provided with an air outlet hole. An adjustable air intake fan 1-3.1 is installed on the outside of the furnace body 1 corresponding to the air inlet hole, and an adjustable air exhaust fan 1-3.2 is installed on the outside of the furnace body 1 corresponding to the air outlet hole.

[0033] Furthermore, the intake fan 1-3.1 is connected to the upper end face of the furnace body 1 via a detachable filter element mounting base 1-3.2.1. A HEPA filter 1-3.2.1.1 with a filtration accuracy of not less than 0.3μm is snapped into the filter element mounting base 1-3.2.1. The HEPA filter 1-3.2.1.1 is used to filter air impurities entering the cooling chamber 1-3.

[0034] Furthermore, the barrier plates 3 are all made of high-temperature resistant ceramic substrates, and the surface of the barrier plate 3 facing the heating cavity 1-1 is covered with a high-alumina ceramic reflective layer. The high-alumina ceramic reflective layer is used to compensate for the heat radiation loss of the heating cavity 1-1 due to the absence of the left side wall.

[0035] Furthermore, the outer wall of the cooling chamber 1-3 of the furnace body 1, which is far from the transition chamber 1-2 (i.e. far from the baffle plate 3), adopts a bolt-removable connection structure, and a high-temperature resistant sealing strip is provided at the joint between the side wall and the frame of the furnace body 1; this facilitates inspection and maintenance as well as assembly.

[0036] Working principle of this utility model: I. Initial Preparation Stage: 1. Under the action of the lifting mechanism 4, the two baffle plates 3 descend to the lowest point, and the lower sealing baffle 3-1 extends into the bottom groove 1-4 of the furnace body 1, cooperating with the ceramic guide rail 1-5 and the lead screw 1-6 to seal and divide the interior of the furnace body 1 into independent heating chamber 1-1, transition chamber 1-2, and cooling chamber 1-3. 2. The heating components (silicon molybdenum rod and silicon carbide rod) of the heating chamber 1-1 and transition chamber 1-2 are in a de-energized state, the inlet fan 1-3.1 and exhaust fan 1-3.2 of the cooling chamber 1-3 are on standby, all furnace doors 5 are closed, the HEPA filter 1-3.2.1.1 is installed in place, and the material tray 2 is located in the heating chamber 1-1.

[0037] II. Sample placement and heating / sintering stage: 1. Sample placement: Open the furnace door 5 of heating chamber 1-1, place the sample to be sintered (low toughness ceramic material) on the material tray 2, and close the furnace door 5.

[0038] 2. Heating Start-up and Constant Temperature Sintering: By setting the target temperature (e.g., 1700℃) and constant temperature time for heating chamber 1-1, the PLC receives the command and starts the first heating component 1-1.1 (silicon molybdenum rod heating element). The silicon molybdenum rods on the top wall, right side wall, and rear side wall operate independently at preset power (the temperature inside the chamber is fed back in real time by the temperature acquisition module, and the PLC dynamically adjusts the power of each silicon molybdenum rod), ensuring that the temperature inside heating chamber 1-1 rises uniformly. The high-alumina ceramic reflective layer of the baffle plate 3 reflects the heat radiation generated by the silicon molybdenum rods towards the heating chamber 1-1, compensating for the heat loss due to the lack of heating elements on the left side wall of heating chamber 1-1, and maintaining a stable temperature field inside the chamber. When the temperature of heating chamber 1-1 reaches the target value, the PLC controls the first heating component 1-1.1 to enter the constant temperature mode, maintaining a stable temperature until the sample is sintered.

[0039] III. Transitional Cooling Phase (Prevention of Thermal Shock): 1. Chamber switching preparation: Before sintering is completed, the PLC starts the second heating component 1-2.1 (silicon carbide heating element) to stabilize the temperature of the transition chamber 1-2 in the range of 1400-1600℃, so as to avoid the sample cracking due to thermal shock caused by directly entering the low temperature environment from the high temperature; after sintering is completed, the PLC shuts off the first heating component 1-1.1 and starts the lifting mechanism 4 corresponding to the baffle plate 3 near the heating chamber 1-1 - the cylinder 4-3 drives the baffle plate 3 to rise along the guide rod 4-1 (the universal floating joint 4-4 compensates for slight offset to ensure smooth lifting), opening the channel between the heating chamber 1-1 and the transition chamber 1-2.

[0040] 2. Sample Transfer: The asynchronous motor 1-7 starts and drives the lead screw 1-6 to rotate through the coupling. The material tray 2 is smoothly transferred from the heating chamber 1-1 to the transition chamber 1-2 with the cooperation of the ceramic guide rail 1-5 and the ceramic slider (smooth sliding without jamming). The lifting mechanism 4—cylinder 4-3—corresponding to the baffle plate 3 near the heating chamber 1-1 is activated to drive the baffle plate 3 to descend along the guide rod 4-1. By gradually reducing the power of the silicon carbide rod, the transition chamber 1-2 and the sample are synchronously cooled from 1700℃ to 800℃, and the cooling rate is stably controlled at 3-8℃ / min.

[0041] IV. Active Cooling Phase: 1. Chamber switching: When the temperature of transition chamber 1-2 drops to 800℃ (i.e., the end temperature of the high-temperature sensitive section, at which point the low-toughness ceramic's resistance to thermal stress is significantly improved), the PLC starts the lifting mechanism 4 of the baffle plate 3 near the cooling chamber 1-3. The baffle plate 3 rises to open the channel between transition chamber 1-2 and cooling chamber 1-3, and the asynchronous motor 1-7 drives the material tray 2 to transfer to the cooling chamber 1-3 again. After the material tray 2 is in place, the baffle plate 3 near the cooling chamber 1-3 descends to reset and seal, and the PLC shuts down the second heating component 1-2.1 (silicon carbide rod heating element).

[0042] 2. Active Cooling: The PLC activates the inlet fan 1-3.1 and exhaust fan 1-3.2 of the cooling chamber 1-3 (the fan speed is adjustable, such as an initial fan speed of 1.5 m / s, which is gradually reduced as the sample temperature decreases). External air, filtered through a HEPA filter 1-3.2.1.1, enters the cooling chamber 1-3 through the inlet vent, exchanging heat with the high-temperature sample. The heated air is then exhausted through the outlet vent by the exhaust fan 1-3.2, achieving rapid sample cooling.

[0043] V. Sample Removal: After cooling is complete (the temperature acquisition module reports that the sample temperature meets the standard), open the furnace door 5 of cooling chamber 1-3 and take out the sample.

[0044] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A laboratory box-type resistance furnace, comprising a furnace body, characterized in that, The furnace body is provided with a material tray that can slide along its length; two baffle plates are inserted at intervals along its length, the upper ends of the baffle plates extend to the outside of the furnace body, and each baffle plate is provided with a lifting mechanism at its upper end. The lifting mechanism is used to drive the baffle plate to move up and down along the height of the furnace body. When both of the aforementioned baffles descend to their lower end faces and seal against the bottom of the furnace body, the internal space of the furnace body is divided from right to left into a heating chamber for workpiece sintering heating, a transition chamber for workpiece cooling buffering, and a cooling chamber for workpiece active cooling. The heating chamber and cooling chamber are respectively hinged to furnace doors on the same side of the furnace body.

2. The laboratory box-type resistance furnace according to claim 1, characterized in that, The bottom of the furnace body has three parallel grooves, which are arranged along the length of the furnace body and pass through the heating chamber, transition chamber and cooling chamber; ceramic guide rails are provided in the grooves on both sides, and a lead screw is rotatably installed in the middle groove. The lower end of the material tray is provided with a ceramic slider that is slidably adapted to the ceramic guide rail, and a screw nut that is threadedly adapted to the screw. One end of the screw is rotatably connected to the inner wall of the middle groove, and the other end extends out of the furnace body and is connected to the output shaft of the asynchronous motor through a coupling.

3. The laboratory box-type resistance furnace according to claim 2, characterized in that, Each of the barrier plates has an integrally extended sealing baffle that extends into the groove on its lower end face. The sealing baffle has a through groove that adapts to the contour of the ceramic guide rail and avoids the lead screw.

4. The laboratory box-type resistance furnace according to claim 1, characterized in that, Each lifting mechanism includes two guide rods arranged parallel to each other along the height of the furnace body. The two guide rods are respectively inserted into guide holes near the two ends of the corresponding baffle plates, and the baffle plates and guide rods are slidably engaged. The lower ends of the two guide rods extend to the bottom of the furnace body and are fixedly connected to the bottom of the furnace body. The upper ends extend upwards out of the baffle plates and are connected to an inverted U-shaped mounting plate. The mounting plate spans above the baffle plates and its two ends are connected to the upper end face of the furnace body. A cylinder is provided in the middle of the horizontal section of the mounting plate. The output shaft of the cylinder passes downwards through the mounting plate and is connected to the upper end face of the corresponding baffle plate.

5. The laboratory box-type resistance furnace according to claim 4, characterized in that, The output shaft of the cylinder is connected to the upper end face of the corresponding baffle plate through a cylinder universal floating joint.

6. The laboratory box-type resistance furnace according to claim 1, characterized in that, The top wall, the right side wall away from the baffle plate, and the rear side wall away from the furnace door of the heating chamber are all provided with a first heating assembly. The first heating assembly includes a silicon molybdenum rod heating element. The silicon molybdenum rod heating elements on the top wall are evenly arranged along their width direction, the silicon molybdenum rod heating elements on the right side wall are equidistantly spaced along their height direction, and the silicon molybdenum rod heating elements on the rear side wall are equidistantly spaced along their length direction.

7. The laboratory box-type resistance furnace according to claim 1, characterized in that, The front, rear, and top walls of the transition cavity are each provided with a second heating assembly, which includes a silicon carbide heating element. The silicon carbide heating elements on the front and rear walls are arranged at equal intervals along their height direction, and the silicon carbide heating elements on the top wall are arranged at equal intervals along their width direction.

8. The laboratory box-type resistance furnace according to claim 1, characterized in that, The cooling chamber has an air inlet hole at the top and an air outlet hole on the side wall. An adjustable air intake fan is installed on the outside of the furnace body corresponding to the air inlet hole, and an adjustable exhaust fan is installed on the outside of the furnace body corresponding to the air outlet hole.

9. The laboratory box-type resistance furnace according to claim 8, characterized in that, The air intake fan is connected to the upper surface of the furnace body via a filter element mounting base, and a HEPA filter is snapped into the filter element mounting base.

10. The laboratory box-type resistance furnace according to claim 1, characterized in that, The barrier plates are all made of high-temperature resistant ceramic substrates, and the surface of the barrier plate facing the heating cavity is covered with a high-alumina ceramic reflective layer.

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