Tube furnace capable of automatically feeding

Abstract

The invention aims to provide a tube furnace capable of automatically feeding, which belongs to the technical field of high-temperature heat treatment electric furnaces and comprises a supporting box body, a furnace tube is arranged in the supporting box body, an electromagnetic driving component is arranged on the furnace tube, and a magnetic conductive crucible capable of linearly moving along the furnace tube is arranged in the furnace tube. One end of the furnace tube is provided with a detection assembly used for detecting the position of the crucible, the other end of the furnace tube is provided with a tube wall cleaning assembly, the two ends of the furnace tube are respectively provided with an atmosphere control assembly, the bottom of the supporting box body is provided with a PLC, and the electromagnetic driving assembly, the detection assembly, the tube wall cleaning assembly and the atmosphere control assemblies are respectively connected with the PLC. According to the tubular furnace, automatic and accurate conveying of samples can be achieved, and in-situ efficient cleaning of the furnace tube can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature heat treatment electric furnace technology, specifically relating to a tubular furnace with automatic feeding capability. Background Technology

[0002] Tube furnaces, as a key high-temperature heat treatment device, are widely used in processes such as sintering, annealing, atmosphere reduction / oxidation, and chemical vapor deposition (CVD). Their core component is the high-temperature resistant furnace tube, and samples are typically placed in crucibles or boats and fed into the furnace tube for heating. Traditional tube furnaces often use manual push-pull rods for sample transport. Manual operation is difficult to perform precisely, has poor repeatability, and is challenging to adjust in real-time during the reaction. The push rod itself also becomes a potential source of contamination and a point of failure.

[0003] To achieve automatic feeding and unloading in tubular furnaces, existing technologies mainly employ the following methods: CN108020090A designs a material feeding and unloading device for tubular furnaces to achieve continuous feeding. Specifically, it discloses that with the partition closed, a coal sample is loaded into the hopper in the material preparation chamber. After the tubular furnace heats to the preset temperature, the partition is opened, and a material rod is used to push the hopper from the material preparation chamber through the exhaust chamber into the furnace reaction zone. After the material rod is pulled back to the preparation chamber, the partition is closed, achieving immediate feeding in a sealed environment and preventing premature reaction of the material during the heating phase. After the reaction is complete, the partition is opened again, the material rod is inserted, rotated, hooked onto the outer edge of the hopper, and pulled back to the preparation chamber. Closing the partition allows for continuous operation.

[0004] The aforementioned prior art for feeding tubular furnaces involves using a feed rod to push the material into the furnace reaction zone. However, mechanical feed rods are susceptible to thermal expansion, furnace tube deformation, or sample residue, which can lead to jamming, positional misalignment, or even damage to the furnace tube seal.

[0005] Furthermore, during repeated high-temperature treatments, especially when volatile substances or powder samples are involved, residues inevitably accumulate on the inner wall of the furnace tube. These residues not only contaminate subsequent experimental samples, affecting the accuracy of results, but may also alter the thermal radiation characteristics of the furnace tube, and even cause localized overheating and damage. Existing cleaning methods mainly rely on manual disassembly of the furnace tube after shutdown for physical or chemical cleaning, a cumbersome and time-consuming process that interrupts production or experimental progress, significantly reducing equipment utilization and experimental efficiency. The lack of effective in-situ cleaning methods restricts the continuous and stable operation of tubular furnaces.

[0006] Meanwhile, precise atmosphere control is crucial for many heat treatment processes. In existing technologies, atmosphere replacement, start-up, shutdown, and maintenance primarily rely on operator experience and manual valve operation. There is a lack of real-time online monitoring and feedback control of the actual atmosphere state within the furnace tubes. This results in low atmosphere replacement efficiency, inaccurate start-up and shutdown timing, and difficulty in achieving precise, automatic, and on-demand control of atmosphere conditions, thus affecting process reproducibility and product quality.

[0007] Therefore, there is an urgent need in this field for an innovative tubular furnace that can simultaneously solve the problems of automated and precise sample delivery, efficient in-situ cleaning of furnace tubes, and intelligent closed-loop control of atmosphere. Summary of the Invention

[0008] The purpose of this invention is to provide an automatically fed tubular furnace that can achieve automated and precise sample delivery and efficient in-situ cleaning of the furnace tubes.

[0009] The present invention adopts the following technical solution: An automatically feeding tubular furnace includes a support box, a furnace tube inside the support box, an electromagnetic drive assembly on the furnace tube, a magnetically conductive crucible that can move linearly along the furnace tube inside the furnace tube, a detection assembly for detecting the position of the crucible at one end of the furnace tube, a tube wall cleaning assembly at the other end, atmosphere control assemblies at both ends of the furnace tube, and a PLC controller at the bottom of the support box. The electromagnetic drive assembly, detection assembly, tube wall cleaning assembly, and atmosphere control assembly are respectively connected to the PLC controller.

[0010] Furthermore, the furnace tube is a quartz tube, and both ends of the quartz tube are provided with flange bases with hollow channels.

[0011] Furthermore, the electromagnetic drive assembly includes a coil power supply and a drive coil unit fitted onto the furnace tube. The drive coil unit includes three sets of coil assemblies with independent windings arranged in parallel. The output end of the coil power supply is connected to the drive coil unit, and the input end of the coil power supply is connected to the output end of the PLC controller.

[0012] Furthermore, the drive coil unit includes a flat copper strip and a cooling tube sleeved on the furnace tube, the flat copper strip and the cooling tube are wrapped with a ceramic fiber layer, and the ceramic fiber layer is wrapped with a stainless steel layer.

[0013] Furthermore, the magnetically conductive crucible includes an arc-shaped crucible body, a groove at the bottom of the crucible body, a permanent magnet in the groove, the N / S pole midline of the permanent magnet being perpendicular to the axis of the furnace tube, and a crucible cover on the crucible body.

[0014] Furthermore, the detection component includes a support frame connected to a flange base, and an infrared laser rangefinder mounted on the support frame, which is connected to a PLC controller.

[0015] Furthermore, the pipe wall cleaning assembly includes a rotating nozzle that passes through the center of a flange base at one end via a bearing. One end of the rotating nozzle is connected to an air pipe via a rotary joint. The outer wall of the rotating nozzle is connected to a transmission gear via a toothed connection. One end of the transmission gear is connected to a motor. The air inlet end of the rotating nozzle is connected to a nozzle rotation unit. A sealing ring is provided between the rotating nozzle and the flange base. The other end of the flange base is connected to a cleaning collection unit. The cleaning collection unit includes a flange flange joint connected to the flange base. The flange flange joint is connected to a rubber tube. The flange base and the flange flange joint are fastened by a clamp. A rubber ring is provided between the flange base and the flange flange joint.

[0016] Furthermore, the rotating nozzle includes a fixed substrate nozzle and a rotating adjustment cover arranged coaxially. The surface of the fixed substrate nozzle is provided with a plurality of spray holes inclined toward the wall of the furnace tube, and the surface of the rotating adjustment cover is provided with a plurality of through holes of the same size as the spray holes of the fixed substrate nozzle. When the rotating adjustment cover rotates relative to the fixed substrate nozzle, the overlapping area of ​​the two arrays of holes changes.

[0017] Furthermore, the rotary adjustment cover includes a nozzle layer with internal threads, a flared sleeve connected to the nozzle layer with internal threads, an annular track groove on the inner side of the flared sleeve, and a plurality of positioning grooves evenly spaced in the annular track groove; the inner side of the rotary adjustment cover is provided with an elastic pressing member, the elastic pressing member including a corrosion-resistant spring, one end of the corrosion-resistant spring being connected to the rotary adjustment cover, and the other end being provided with a ceramic bead, the ceramic bead being partially embedded in the positioning groove to achieve gear locking.

[0018] Furthermore, the edge of the rotating adjustment cover is provided with an operating handle.

[0019] Furthermore, the nozzle rotation unit includes a ball joint bearing rotatably connected to the flange base, one end of the ball joint bearing is connected to a screw support, one end of the screw support is connected to a rolling bearing, and the end of the rotating nozzle passes through the rolling bearing.

[0020] Furthermore, the atmosphere control component includes an oxygen analyzer and a flow meter located at both ends of the furnace tube, respectively. The oxygen analyzer is connected to the input terminal of the PLC controller, and the flow meter is connected to the output terminal of the PLC controller.

[0021] The beneficial effects of this invention are as follows: 1. This invention only requires placing the magnetic crucible inside the furnace tube, and the magnetic crucible can automatically transport materials to the designated location via electromagnetic drive. The infrared laser rangefinder can accurately position the carrier crucible, avoiding the inability to accurately control the sample's position in the temperature zone when manually pushing the sample, the increased frictional resistance caused by residue after the carrier crucible is accidentally overturned, and the reduction of external contaminants carried into the furnace tube by the push rod.

[0022] 2. This invention uses a rotating jet assembly to carry away sample residues from the tube wall with airflow. The high-speed airflow covers the entire furnace tube and can be automatically activated at the end of the process, achieving immediate cleaning. This effectively avoids the adhesion of sintered volatiles from powder samples to the tube wall, which alters the heat field distribution and contaminates subsequent samples, as well as the reduced utilization rate due to manual disassembly and cleaning.

[0023] 3. This invention monitors the oxygen at the outlet end using an oxygen analyzer. After receiving the signal, the PLC controller automatically controls the atmosphere using a flow meter, which efficiently reduces gas consumption and automatically records the oxygen content-time curve, providing a basis for process optimization. This avoids relying on manual experience to replace the atmosphere, excessive introduction of protective gas, and premature heating when the oxygen content is not up to standard, which can lead to sample oxidation. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the tubular furnace of the present invention; Figure 2 This is a schematic diagram of the drive coil unit. Figure 3 This is a schematic diagram of the structure of a magnetically conductive crucible; Figure 4 This is a schematic diagram showing the meshing of the toothed teeth of the rotating nozzle with the gears of the motor drive. Figure 5 A schematic diagram of the structure of the trumpet-shaped sleeve for rotating the adjustment cover; Figure 6 This is a schematic diagram of the rotating nozzle structure; Figure 7 This is a schematic diagram of the nozzle rotation unit. Figure 8 This is a schematic diagram of the cleaning collection unit. The components are as follows: 1-Support box; 2-Furnace tube; 3-PLC controller; 4-Flange base; 5-Coil power supply; 6-Drive coil unit; 7-Flat copper strip; 8-Cooling pipe; 9-Ceramic fiber layer; 10-Stainless steel layer; 11-Crucible body; 12-Crucible lid; 13-Permanent magnet; 14-Support frame; 15-Infrared laser rangefinder; 16-Rotating nozzle; 17-Rotating joint; 18-Gas pipe; 19-Transmission gear; 20-Motor; 21-Nozzle rotating unit; 22-Flange flange joint; 23-Rubber tube; 24-Clamp; 25-Fixed substrate nozzle; 26-Rotating adjustment cover; 27-Spray hole layer; 28-Flare sleeve; 29-Annular track groove; 30-Corrosion resistant spring; 31-Ceramic bead; 32-Operating handle; 33-Spherical bearing; 34-Screw bracket; 35-Rolling bearing; 36-Oxygen analyzer; 37-Flow meter. Detailed Implementation

[0025] The invention will be further described with reference to the accompanying drawings.

[0026] As shown in the figure, an automatic feeding tube furnace includes a support box 1, a furnace tube 2 inside the support box 1, an electromagnetic drive assembly on the furnace tube 2, a magnetic crucible that can move linearly along the furnace tube 2 inside the furnace tube 2, a detection assembly for detecting the position of the crucible at one end of the furnace tube 2, a tube wall cleaning assembly at the other end, atmosphere control assemblies at both ends of the furnace tube 2, and a PLC controller 3 at the bottom of the support box 1. The electromagnetic drive assembly, the detection assembly, the tube wall cleaning assembly, and the atmosphere control assembly are all connected to the PLC controller 3.

[0027] The support box 1 is equipped with a heating device. The furnace tube 2 is fixed on the support box 1. The electromagnetic drive assembly is connected to the furnace tube 2. The magnetic crucible can move linearly in the furnace tube 2 under the drive of the electromagnetic drive assembly. The PLC controller 3 is located inside the support box 1 and is connected to the electromagnetic drive assembly and the crucible position detection assembly.

[0028] The furnace tube 2 includes a quartz tube and a flange base 4. The quartz tube is mounted on the support box 1, and the flange base 4 has a hollow channel and is installed on both sides of the quartz tube.

[0029] The electromagnetic drive assembly includes a drive coil unit 6 and a coil power supply 5. The drive coil unit 6 includes three sets of coil assemblies, which are independently wound and arranged in parallel, namely coil assembly one, coil assembly two, and coil assembly three. Each coil assembly includes a flat copper strip 7, a cooling pipe 8, a ceramic fiber layer 9, and a stainless steel layer 10. The flat copper strip 7 and the cooling pipe 8 are sleeved on the outside of the furnace tube 2. The flat copper strip 7 and the cooling pipe 8 are wrapped inside the ceramic fiber layer 9. The stainless steel layer 10 is sleeved on the outside of the ceramic fiber layer 9. The coil assembly is connected to the PLC controller 3 and the coil power supply 5.

[0030] The magnetic crucible includes a crucible body 11, a crucible cover 12, and a permanent magnet 13. The bottom of the crucible body 11 has a cuboid groove, and the permanent magnet 13 is disposed in the cuboid groove. The N / S pole midline of the permanent magnet 13 is perpendicular to the axial direction of the furnace tube 2.

[0031] The detection component includes a support frame 14 and an infrared laser rangefinder 15. The two ends of the support frame 14 are respectively connected to the flange base 4 and the infrared laser rangefinder 15. The infrared laser rangefinder 15 is connected to the PLC controller 3.

[0032] The staff can achieve electromagnetic drive automatic transportation by placing the carrier crucible inside the furnace tube 2. When the infrared laser rangefinder 15 detects the carrier crucible, it will immediately energize the coil assembly.

[0033] The magnetic field generated by the coil has the same polarity as the front half of the permanent magnet 13 inside the carrier crucible, which generates a pushing force into the furnace tube 2, causing the carrier crucible to move. When the carrier crucible moves towards the coil assembly 2, the PLC controller 3 receives the signal from the infrared laser rangefinder 15 and powers the coil assembly 2. The magnetic field generated by the coil assembly 1 towards the rear half of the permanent magnet 13 inside the carrier crucible is repulsive, and the magnetic field generated by the coil assembly 2 towards the front half of the permanent magnet 13 inside the carrier crucible is attractive, driving the carrier crucible to move.

[0034] When the infrared laser rangefinder 15 detects that the carrier crucible has reached the designated position, the PLC controller 3 implements a step-by-step current cutoff. First, the current of the current coil is cut off, and after 10ms, the current of the next coil is cut off. The thrust is used to buffer and decelerate. After 20ms, the current of the last group of coils is cut off, so that the magnetic force returns to zero and the crucible comes to rest.

[0035] The in-situ high-efficiency tube furnace with furnace tube 2 achieves tube wall cleaning function through the coordinated action of tube wall cleaning component 6 and PLC controller 8.

[0036] The pipe wall cleaning assembly includes a rotating nozzle 16, an air pipe 18, a transmission gear 19, a motor 20, and a nozzle rotation unit 21. The rotating nozzle 16 passes through the center of the flange base 4 via a bearing. The air pipe 18 is connected to one end of the rotating nozzle 16 via a rotary joint 17. The transmission gear 19 is connected to the rotating nozzle 16 via teeth. The motor 20 is connected to the center of the transmission gear 19. The nozzle rotation unit 21 is connected to the air inlet end of the rotating nozzle 16.

[0037] The rotating nozzle 16 includes a fixed substrate nozzle 25 and a rotating adjustment cover 26. The surface of the fixed substrate nozzle 25 is provided with multiple angled nozzles that are inclined to the pipe wall. The surface of the rotating adjustment cover 26 is distributed with through holes of the same size as the nozzles of the fixed substrate nozzle 25. When the rotating adjustment cover 26 rotates relative to the fixed substrate nozzle 25, the overlapping area of ​​the two arrays of holes changes.

[0038] The rotating adjustment cover 26 includes a nozzle layer 27 and a horn-shaped sleeve 28. The inner side of the horn-shaped sleeve 28 is provided with an annular track groove 29, and multiple positioning recesses are evenly distributed in the groove. An elastic pressing member is installed on the inner side of the rotating adjustment cover 26. The elastic pressing member is composed of a corrosion-resistant spring 30 and a ceramic bead 31. The ceramic bead 31 is partially embedded in the positioning recess to achieve gear locking. The outer edge of the rotating adjustment cover 26 extends to form a radially protruding operating handle 32. The surface of the operating handle 32 is provided with laser-etched anti-slip texture, and a visual angle indicator mark is provided on its back. The mark is matched with the reference scale on the edge of the fixed substrate nozzle 25 to show the adjustment status.

[0039] The nozzle rotation unit 21 includes a ball joint bearing 33, a screw support 34, and a rolling bearing 35. The ball joint bearing 33 is disposed in the flange base 4. The screw support 34 is connected to the ball joint bearing 33. The rolling bearing 35 connects the tail of the rotating nozzle 16 and the screw support 34.

[0040] A sealing assembly is provided between the rotary nozzle 16 and the flange base 4.

[0041] The cleaning and collection unit includes a flange flange joint 22 connected to the flange base 4, a rubber tube 23 connected to the flange flange joint 22, a clamp 24 for fixing the connection between the flange base 4 and the flange flange joint 22, and a rubber ring placed between the flange base 4 and the flange flange joint 22.

[0042] The operator can set in advance on the PLC controller 3 whether to rotate and purge the pipe wall. Place a rubber ring between the flange base 4 and the flange flange joint 22, connect them with clamps 24, and manually turn the screw bracket 34 of the nozzle rotation unit to adjust the nozzle direction. Manually adjust the operating handle 32 of the rotating adjustment cover 26 to make the rotating adjustment cover 26 rotate relative to the fixed base plate nozzle 25. The overlapping area of ​​the holes changes, thus adjusting the size of the air hole. After the setting is completed, the PLC controller 3 powers on the motor 20 to drive the rotating nozzle 16 to rotate.

[0043] The atmosphere reaches the rotating nozzle 16 through the gas path. The centripetal force generated by the rotation changes the direction of the jet, forming a spiral airflow that washes away the deposits on the inner wall of the furnace tube 2 at high speed, achieving full coverage of the jet tube wall. After cleaning, the gas source and motor 20 are turned off.

[0044] The atmosphere control component includes an oxygen analyzer 36 and a flow meter 37. The oxygen analyzer 36 is located at one end of the furnace tube 2 and connected to the input terminal of the PLC controller 3, and the flow meter 37 is connected to the output terminal of the PLC controller 3.

[0045] After the staff connects the gas tube 18 to the atmosphere required for the reaction, they click to turn on the atmosphere on the display screen, set the gas flow rate during the reaction, and the PLC controller 3 controls the flow meter 37 to turn on. At the same time, the oxygen analyzer 36 monitors the atmosphere. When the oxygen analyzer 36 detects that the oxygen content reaches the specified value and the fluctuation range of the atmospheric oxygen concentration does not exceed ±0.1%, the PLC controller 3 controls the flow meter 37 to adjust to the gas flow rate during the reaction.

[0046] Staff can set in advance whether to record oxygen concentration in real time. During the reaction, PLC controller 3 will record in real time and generate an oxygen content-time curve at the end of the reaction.

[0047] During the reaction, the atmosphere control components regulate the furnace environment in real time. The oxygen analyzer 36 at the outlet continuously monitors the oxygen content of the exhaust gas, and the data is fed back to the PLC controller 3 in real time. When the oxygen content exceeds the set threshold, the PLC controller 3 adjusts the inlet solenoid valve to increase the protective gas flow; the flow is automatically adjusted back after the oxygen content returns to normal.

[0048] During equipment operation, PLC controller 3 displays the displacement coordinates of the magnetic crucible and the oxygen concentration curve in real time.

[0049] The working principle of this invention is as follows: When the staff needs to use the tube furnace, they first set the required reaction temperature, time, atmosphere flow rate, whether to record the oxygen concentration in real time, and whether to rotate and purge the tube wall. They then manually adjust the nozzle rotation unit 21 and the rotating adjustment cover 26. After that, they put the sample into the magnetic crucible, put the crucible cover 12 on it, place it in one end of the quartz tube, close the flange, and start the tube furnace on the PLC controller 3. The PLC controller 3 displays the displacement coordinates of the magnetic crucible, the temperature inside the furnace tube 2, the atmosphere flow rate, and the oxygen concentration inside the tube in real time.

[0050] After the reaction ends and the temperature drops, the sample is automatically transported to one end of the quartz tube. The operator replaces the flange base 4 with a cleaning collection unit. The operator can choose whether the tube wall cleaning component continues to operate and increase the airflow, and export the oxygen concentration curve. The residue inside the furnace tube is then purged into the rubber tube 23. After purging, the PLC controller 3 shuts off the gas source and motor 20, and the oxygen concentration curve is exported.

Claims

1. A tubular furnace with automatic feeding capability, characterized in that: The system includes a support box (1), a furnace tube (2) is provided inside the support box (1), an electromagnetic drive assembly is provided on the furnace tube (2), a magnetic crucible that can move linearly along the furnace tube (2) is provided inside the furnace tube (2), a detection assembly for detecting the position of the crucible is provided at one end of the furnace tube (2), a tube wall cleaning assembly is provided at the other end, an atmosphere control assembly is provided at both ends of the furnace tube (2), a PLC controller (3) is provided at the bottom of the support box (1), and the electromagnetic drive assembly, detection assembly, tube wall cleaning assembly and atmosphere control assembly are respectively connected to the PLC controller (3).

2. The tubular furnace with automatic feeding according to claim 1, characterized in that: The furnace tube (2) is a quartz tube, and both ends of the quartz tube are provided with flange bases (4) with hollow channels.

3. The tubular furnace with automatic feeding according to claim 1, characterized in that: The electromagnetic drive assembly includes a coil power supply (5) and a drive coil unit (6) sleeved on the furnace tube (2). The drive coil unit (6) includes three sets of coil assemblies with independent windings arranged in parallel. The output end of the coil power supply (5) is connected to the drive coil unit (6), and the input end of the coil power supply (5) is connected to the output end of the PLC controller (3). The drive coil unit (6) includes a flat copper strip (7) and a cooling pipe (8) sleeved on the furnace tube (2). The flat copper strip (7) and the cooling pipe (8) are wrapped with a ceramic fiber layer (9), and the ceramic fiber layer (9) is wrapped with a stainless steel layer (10).

4. The tubular furnace with automatic feeding according to claim 1, characterized in that: The magnetic crucible includes an arc-shaped crucible body (11), with a groove at the bottom of the crucible body (11) and a permanent magnet (12) inside the groove. The N / S pole midline of the permanent magnet (13) is perpendicular to the axis of the furnace tube (2), and a crucible cover (12) is provided on the crucible body (11).

5. A tubular furnace with automatic feeding according to claim 2, characterized in that: The detection component includes a support frame (14), which is connected to a flange base (4). An infrared laser rangefinder (15) is mounted on the support frame (14), and the infrared laser rangefinder (15) is connected to a PLC controller (3).

6. A tubular furnace with automatic feeding according to claim 2, characterized in that: The pipe wall cleaning assembly includes a rotating nozzle (16) that passes through the center of a flange base (4) at one end via a bearing. One end of the rotating nozzle (16) is connected to an air pipe (18) via a rotating joint (17). The outer wall of the rotating nozzle (16) is connected to a transmission gear (19) via a toothed connection. One end of the transmission gear (19) is connected to a motor (20). The air inlet end of the rotating nozzle (16) is connected to a nozzle rotating unit (21). A sealing ring is provided between the rotating nozzle (16) and the flange base (4). The other end of the flange base (4) is connected to a cleaning collection unit. The cleaning collection unit includes a flange flange joint (22) connected to the flange base (4). The flange flange joint (22) is connected to a rubber tube (23). The flange base (4) and the flange flange joint (22) are fastened by a clamp (24). A rubber ring is provided between the flange base (4) and the flange flange joint (22).

7. A tubular furnace with automatic feeding according to claim 6, characterized in that: The rotating nozzle (16) includes a fixed substrate nozzle (25) and a rotating adjustment cover (26) arranged coaxially. The surface of the fixed substrate nozzle (25) is provided with a number of spray holes that are inclined toward the wall of the furnace tube (2). The surface of the rotating adjustment cover (26) is provided with a number of through holes that are the same size as the spray holes of the fixed substrate nozzle (25).

8. A tubular furnace with automatic feeding according to claim 6, characterized in that: The rotary adjustment cover (26) includes a nozzle layer (27) with internal threads and a horn-shaped sleeve (28) internally threaded to the nozzle layer (27). The inner side of the horn-shaped sleeve (28) is provided with an annular track groove (29), and the annular track groove (29) is provided with a plurality of positioning grooves at equal intervals. The inner side of the rotary adjustment cover (26) is provided with an elastic pressing member, which includes a corrosion-resistant spring (30). One end of the corrosion-resistant spring (30) is connected to the rotary adjustment cover (26), and the other end is provided with a ceramic bead (31). The ceramic bead (31) is partially embedded in the positioning groove to achieve gear locking. The edge of the rotating adjustment cover (26) is provided with an operating handle (32).

9. A tubular furnace with automatic feeding according to claim 6, characterized in that: The nozzle rotation unit (21) includes a ball joint bearing (33) rotatably connected to the flange base (4). One end of the ball joint bearing (33) is connected to a screw support (34), and one end of the screw support (34) is connected to a rolling bearing (35). The end of the rotating nozzle (16) passes through the rolling bearing (35).

10. A tubular furnace with automatic feeding according to claim 1, characterized in that: The atmosphere control assembly includes an oxygen analyzer (36) and a flow meter (37) located at both ends of the furnace tube (2). The oxygen analyzer (36) is connected to the input terminal of the PLC controller (3), and the flow meter (37) is connected to the output terminal of the PLC controller (3).

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