Vacuum tube furnace

Abstract

The present invention discloses a vacuum tube furnace, specifically relating to the technical field of rubidium magnet anti-corrosion, and includes the following steps: Magnet pretreatment: After pickling the sintered NdFeB magnet, ultrasonic cleaning is carried out in deionized water, and then it is transferred to absolute ethanol for dehydration treatment; Sputtering an Al-Cu alloy film on the magnet surface: Use a magnetron sputtering coater to sputter an Al-Cu film on the surface of the NdFeB magnet, with the ratio of Al:Cu in the target being 1:1; Diffusing an Al-Cu alloy layer on the magnet surface: Place the coated NdFeB magnet in a vacuum tube furnace for diffusion under the conditions of a vacuum degree of 10-3 to 10-4 Pa, a diffusion temperature of 700°C - 800°C, a heating rate of 5°C / min, and a holding time of 2 h. After the sputtered coating magnet undergoes a thermal diffusion process, on the premise of ensuring the magnetism of the magnet, the corrosion resistance of the magnet is significantly improved.

Description

Technical Field

[0001] The present invention relates to the field of anti-corrosion of rubidium magnets, specifically a vacuum tube furnace. Background Art

[0002] Sintered NdFeB magnets are widely used in fields such as machinery, electronics, and instruments due to their excellent magnetic properties. NdFeB magnets in harsh environments such as wind power generation have a long-term maintenance-free requirement of more than 25 years. However, due to the multiphase structure of the magnet itself (the main phase Nd2Fe 14 B, Nd-rich phase, and B-rich phase) and the difference in electrochemical potential between each phase, the magnet is prone to corrosion, resulting in failure. The poor inherent corrosion resistance of NdFeB magnets has become a bottleneck for the further development of surface protection technology.

[0003] The existing protection methods for NdFeB magnets are divided into alloying method and surface protection method. The alloying method reduces the potential difference, but at the same time will cause a certain degree of loss of the magnetic properties of the magnet; while the implementation means of the surface protection method will also be restricted in terms of environmental protection, economy, etc. For example, the electroplating solution and passivation solution used in electroplating and passivation processes are extremely unfriendly to the environment, and Ni in the Ni layer is a precious metal, resulting in high production costs.

[0004] The patent application document with the patent number CN213150565U discloses a NdFeB magnet modification device for grain boundary diffusion metal infiltration, including a feeding chamber, a sputtering diffusion process chamber, a discharging chamber, and a base. The feeding chamber is provided with a three-dimensional workpiece turntable system, an ion source etching system, and a first heating system. The sputtering diffusion process chamber is provided with a sputtering source system, a high-energy ion source system, and a second heating system. The discharging chamber is provided with a third heating system. A NdFeB magnet modification device for grain boundary diffusion metal infiltration of the present invention is rationally configured according to the process flow for preparing high coercivity NdFeB composites. The feeding chamber has the functions of ion etching and preheating, the sputtering diffusion process chamber has the functions of sputtering a metal film and metal diffusion, the discharging chamber has the function of tempering heat treatment, and the three chambers are separated by valves and work independently of each other without interference, realizing the continuity of production.

[0005] However, only forming a film layer on the surface of the rubidium magnet by magnetron sputtering will cause a certain degree of loss of the magnetic properties of the magnet. Summary of the Invention

[0006] The purpose of the present invention is to provide a vacuum tube furnace to solve the technical problem of magnetic loss after sputtering coating as mentioned in the above background art.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] A surface aluminum-copper alloyed NdFeB magnet, characterized in that: there is a thermally diffused aluminum-copper alloy layer on the magnet surface, and the ratio of copper to aluminum is 1:1

[0009] A preparation method of a surface aluminum-copper alloyed NdFeB magnet, comprising the following steps:

[0010] 1) Magnet pretreatment: After pickling the sintered NdFeB magnet, ultrasonically clean it in deionized water, and then transfer it to absolute ethanol for dehydration treatment;

[0011] 2) Sputtering an Al-Cu alloy film on the magnet surface: Use a magnetron sputtering coater to sputter an Al-Cu film on the surface of the NdFeB magnet, and the ratio of Al:Cu in the target is 1:1;

[0012] 3) Diffusing an Al-Cu alloy layer on the magnet surface: Place the coated NdFeB magnet in a vacuum tube furnace under a vacuum degree of 10 -3 ~10 -4 Pa, a diffusion temperature of 700 °C - 800 °C, a heating rate of 5 °C / min, and a holding time of 2 h for diffusion.

[0013] After the magnet after sputtering coating undergoes a thermal diffusion process, on the premise of ensuring the magnetism of the magnet, the corrosion resistance of the magnet is significantly improved.

[0014] Preferably, in step 1), the nitric acid concentration used is 3%, the pickling time is 20 - 30 s; the ultrasonic time is 3 - 5 min.

[0015] Preferably, in step 2), an Al-Cu target with a purity of more than 99.99% is selected for sputtering, the sputtering power is 150 W, the starting glow pressure is 1.0 Pa, the working pressure is 0.5 Pa, and the sputtering coating time is 0.5 - 1 h.

[0016] Meanwhile, a vacuum tube furnace is proposed for the thermal diffusion of metals after magnetron sputtering coating. The technical solution is as follows:

[0017] The vacuum tube furnace includes a control box, the control box is connected to the furnace body above, the furnace body is connected to the furnace cover above, a furnace rack is fixedly connected inside the furnace body, a tube groove is arranged in the middle of the furnace rack, a furnace cavity is placed on the tube groove, both ends of the furnace cavity are respectively connected to a sealing mechanism, the sealing mechanism includes a fixed flange fixedly connected to the furnace cavity, the fixed flange is connected to a sealing flange, the other end of the sealing flange is connected to a packing mechanism, a pressure gauge is connected to the side of the sealing flange, and the sealing flange is connected to the packing mechanism, which can supplement the packing during the thermal diffusion process of the previous magnet. A multi-temperature zone vacuum tube furnace is used to realize the thermal diffusion of multiple magnets under different conditions simultaneously, improving the test efficiency.

[0018] Preferably, the filling mechanism includes a filling pipe communicating with the sealing flange. The end of the filling pipe is connected to a filling cylinder. A filling wheel is rotatably connected inside the filling cylinder. Filling grooves are provided on the filling wheel. An exhaust mechanism, an inflation mechanism, and a cooling mechanism are respectively connected to the side surface of the filling cylinder. A transfer mechanism is provided on the side surface of the furnace cavity.

[0019] Preferably, the filling cylinder is a hollow cylinder with an opening on the side surface. The outer part of the filling wheel fits with the inner wall of the filling cylinder. The filling groove is a cylindrical groove with the same inner diameter as the filling pipe, and the filling groove communicates with the side surface of the filling wheel.

[0020] Preferably, the transfer mechanism includes a chute arranged along the direction parallel to the axis of the furnace cavity and close to the furnace cavity. An electromagnet is arranged in the chute. The electromagnet is threadedly connected to a lead screw. When the electromagnet in the transfer mechanism is energized to generate magnetism to attract the magnet in the filling groove, the electromagnet can move when the lead screw rotates, so that the magnet in the filling groove can move to a specific area in the furnace cavity accordingly, and thermal diffusion is carried out under specific temperature conditions in this area.

[0021] Preferably, the exhaust mechanism includes an exhaust cylinder communicating with one end of the filling cylinder. A guide pipe aligned with the exhaust cylinder is connected to the other end of the filling cylinder. Check valves are respectively connected to the outer ends of the exhaust cylinder and the guide pipe. The air in the filling cylinder is discharged by the method of ventilating at one end and introducing inert gas at the other end, so as to avoid the reaction of the magnet and the coating on it with the components in the air during the thermal diffusion process.

[0022] Preferably, the inflation mechanism includes an inflation pipe communicating with one end of the filling cylinder. An inflation valve is connected to the end of the inflation pipe. A pressure measuring pipe is connected to the position of the filling cylinder aligned with the inflation pipe at the other end. A pressure gauge is connected to the pressure measuring pipe, and the other end of the pressure gauge communicates with the filling pipe. Part of the inert gas is supplemented through the inflation mechanism to make the pressure in the filling groove the same as the pressure in the furnace cavity. After the filling groove rotates to communicate with the furnace cavity, the pressure in the furnace cavity is kept stable.

[0023] Preferably, the cooling mechanism includes a cooling water pipe connected to one end of the filling cylinder. The cooling water pipe is aligned with a cooling flow channel penetrating the filling wheel. A drain port aligned with the cooling flow channel is arranged at the other end of the filling cylinder. The cooling mechanism adopts the method of conduction water cooling, which has a faster cooling rate compared with natural cooling or inert gas cooling, and can avoid the contact of the magnet still in a high-temperature state with the outside.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention adopts a vacuum diffusion technology based on magnetron sputtering to realize the Al-Cu alloying process on the surface layer of NdFeB magnets, significantly improving the corrosion resistance of the magnets. Compared with the traditional magnet alloying technology, the present invention realizes the surface alloying of the magnets instead of the overall alloying, greatly improving the intrinsic corrosion resistance of the magnets and keeping the magnets' own magnetism.

[0026] 2. The vacuum tube furnace provided in the present application is used for the magnet thermal diffusion process. During the diffusion, the magnet can be added to or taken out of the furnace cavity at any time without introducing air, changing the furnace cavity pressure conditions and temperature conditions through the filling mechanism. The multi-temperature zone vacuum tube furnace can be used to heat treat magnets with different process conditions at the same time;

[0027] 3. The filling mechanism adopts a filling wheel with a filling groove on the side that is connected to the filling cylinder in a rotating manner, and the filling cylinder is respectively connected with an exhaust mechanism to realize vacuuming inside the filling groove, and an air charging mechanism is set to make the internal pressure of the filling groove the same as the internal pressure of the furnace chamber, and a cooling mechanism is set to make the taken out magnets quickly cool down under a high vacuum state, thereby improving the heat treatment efficiency;

[0028] 4. The exhaust mechanism adopts the method of introducing inert gas and exhausting at the same time, which can fully squeeze out the air inside the stuffing tank. The two ends of the pressure measuring valve in the inflation mechanism are respectively connected to the stuffing tank and the furnace cavity, and the pressure is observed while inflating until it is balanced;

[0029] 5. The cooling mechanism adopts the method of setting a penetrating cooling channel on the packing wheel. The water takes away the heat during the flow in the channel close to the packing groove. After the heat treatment is completed, the magnet is in a high vacuum state and is quickly cooled by heat conduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a SEM image of the surface of the Al-Cu alloyed high corrosion resistant magnet after thermal diffusion of the present invention;

[0031] Figure 2 The polarization curves of the high corrosion-resistant sintered NdFeB magnet with alloyed surface layer after heat diffusion of the present invention and the control example;

[0032] Figure 3 It is a structural schematic diagram of the vacuum tube furnace of the present invention;

[0033] Figure 4 It is a structural schematic diagram of the packing mechanism of the present invention;

[0034] Figure 5 A half-section view of a packing tube of the present invention;

[0035] Figure 6 is a cross-sectional view of the exhaust mechanism of the present invention;

[0036] Figure 7 It is a structural schematic diagram of the inflation mechanism of the present invention;

[0037] Figure 8 It is a schematic structural diagram of the packing wheel of the present invention.

[0038] In the figure: 1. Control box; 2. Furnace body; 21. Slide groove; 22. Furnace cavity; 3. Furnace cover; 4. Transfer mechanism; 41. Electromagnet; 42. Lead screw; 43. Transfer motor; 5. Filling mechanism; 51. Filling cylinder; 511. Filling port; 52. Filling wheel; 521. Filling groove; 522. Cooling flow channel; 53. Filling motor; 6. Exhaust mechanism; 61. Air duct; 62. Exhaust cylinder; 7. Inflation mechanism; 71. Inflation pipe; 72. Connecting pipe; 73. Pressure gauge; 74. Pressure measuring pipe; 8. Cooling mechanism; 81. Drainage port; 82. Cooling water pipe; 9. Sealing mechanism; 91. Fixed flange; 92. Sealing flange; 93. Filling pipe. Specific embodiments

[0039] Example 1

[0040] S1: After pickling the sintered NdFeB magnet for 30 s, ultrasonicate it in deionized water, and then transfer it to absolute ethanol for dehydration treatment;

[0041] S2: Use a high-purity (99.999%) Al-Cu target and a JGP-450A magnetron sputtering coater to sputter an Al-Cu film on the surface of the NdFeB magnet. The sputtering power is 150 W, the starting glow pressure is 1.0 Pa, the working pressure is 0.5 Pa, and the sputtering coating time is 0.5 h;

[0042] S3: Diffuse the NdFeB magnet coated with the Al-Cu film in a vacuum tube furnace. The vacuum degree is 10-3~10-4 Pa, the diffusion temperature is 700 °C, and the holding time is 2 h;

[0043] According to the above steps, the corrosion potential of the surface alloyed sintered NdFeB magnet in the electrochemical corrosion test is -0.79 V, the self-corrosion current density is 9.173×10-7 A·cm-2, and corrosion occurs after soaking in 3.5 wt% NaCl solution for 48 h. Its comprehensive corrosion resistance is significantly better than that of the control example.

[0044] Example 2:

[0045] S1: After pickling the sintered NdFeB magnet for 30 s, ultrasonicate it in deionized water, and then transfer it to absolute ethanol for dehydration treatment;

[0046] S2: Use a high-purity (99.999%) Al-Cu target and a JGP-450A magnetron sputtering coater to sputter an Al-Cu film on the surface of the NdFeB magnet. The sputtering power is 150 W, the starting glow pressure is 1.0 Pa, the working pressure is 0.5 Pa, and the sputtering coating time is 0.5 h;

[0047] S3: Diffuse the Al-Cu film-coated NdFeB magnet in a vacuum tube furnace. The vacuum degree is 10-3~10-4 Pa, the diffusion temperature is 800 °C, and the heat preservation time is 2 h;

[0048] According to the above steps, the corrosion potential of the surface alloyed sintered NdFeB magnet in the electrochemical corrosion test is -1.08 V, the self-corrosion current density is 2.138×10-6 A·cm-2, corrosion occurs after soaking in 3.5wt% NaCl solution for 30 h, and its comprehensive corrosion resistance is significantly better than that of the control example.

[0049] Example 3:

[0050] S1: Pickle the sintered NdFeB magnet for 30 s, then ultrasonically clean it in deionized water, and then transfer it to absolute ethanol for dehydration treatment;

[0051] S2: Use a high-purity (99.999%) Al-Cu target, and use a JGP-450A magnetron sputtering coater to sputter an Al-Cu film on the surface of the NdFeB magnet. The sputtering power is 150 W, the starting glow pressure is 1.0 Pa, the working pressure is 0.5 Pa, and the sputtering coating time is 1 h;

[0052] S3: Diffuse the Al-Cu film-coated NdFeB magnet in a vacuum tube furnace. The vacuum degree is 10-3~10-4 Pa, the diffusion temperature is 700 °C, and the heat preservation time is 2 h.

[0053] According to the above steps, the corrosion potential of the surface alloyed sintered NdFeB magnet in the electrochemical corrosion test is -1.91 V, the self-corrosion current density is 3.159×10-6 A·cm-2, corrosion occurs after soaking in 3.5wt% NaCl solution for 24 h, and its comprehensive corrosion resistance is significantly better than that of the control example.

[0054] Example 4:

[0055] S1: Pickle the sintered NdFeB magnet for 30 s, then ultrasonically clean it in deionized water, and then transfer it to absolute ethanol for dehydration treatment;

[0056] S2: Use a high-purity (99.999%) Al-Cu target, and use a JGP-450A magnetron sputtering coater to sputter an Al-Cu film on the surface of the NdFeB magnet. The sputtering power is 150 W, the starting glow pressure is 1.0 Pa, the working pressure is 0.5 Pa, and the sputtering coating time is 1 h;

[0057] S3: Diffuse the Al-Cu film-coated NdFeB magnet in a vacuum tube furnace. The vacuum degree is 10-3~10-4 Pa, the diffusion temperature is 800 °C, and the heat preservation time is 2 h.

[0058] According to the above steps, the corrosion potential of the surface alloyed sintered NdFeB magnet obtained in the electrochemical corrosion test is -1.12 V, the self-corrosion current density is 1.211×10-5 A·cm-2, and corrosion occurs after soaking in 3.5wt% NaCl solution for 18 h. Its comprehensive corrosion resistance is significantly better than that of the control example, as Figure 1-2 shown.

[0059] Example 5

[0060] As Figure 3-4 shown, the vacuum tube furnace includes a control box 1. The furnace body 2 is connected above the control box 1, and the furnace cover 3 is connected above the furnace body 2. A furnace rack is fixedly connected inside the furnace body 2. A tube slot is arranged in the middle of the furnace rack, and a furnace chamber 22 is placed on the tube slot. Both ends of the furnace chamber 22 are respectively connected to a sealing mechanism 9. The sealing mechanism 9 includes a fixed flange 91 fixedly connected to the furnace chamber 22. The fixed flange 91 is connected to a sealing flange 92, and the other end of the sealing flange 92 is connected to a packing mechanism 5. A pressure gauge 73 is connected to the side of the sealing flange 92. The packing mechanism 5 includes a packing tube 93 communicating with the sealing flange 92. The end of the packing tube 93 is connected to a packing cylinder 51. A packing wheel 52 is rotatably connected inside the packing cylinder 51. A packing groove 521 is arranged on the packing wheel 52. The side of the packing cylinder 51 is respectively connected to an exhaust mechanism 6, an inflation mechanism 7, and a cooling mechanism 8. A transfer mechanism 4 is arranged on the side of the furnace chamber 22.

[0061] When the magnet after magnetron sputtering needs thermal diffusion, the magnet is sent into the packing groove 521 on the side of the packing wheel 52 rotatably connected inside the packing cylinder 51 through the packing mechanism 5. During the rotation of the packing groove 521, the packing wheel 52 is first driven to rotate until the side of the packing groove 521 fits against the inner wall of the packing cylinder 51. The end of the packing groove 521 communicates with the exhaust mechanism 6, and an inert gas is filled into the packing groove 521 through the exhaust mechanism 6 to expel the internal air. Then, the packing wheel 52 rotates under the drive of the packing motor 53 until the end of the packing groove 521 communicates with the inflation mechanism 7, and gas is supplemented or discharged inside the inflation mechanism 7 to make the pressure inside the packing groove 521 carrying the magnet the same as the pressure inside the furnace chamber 22. The packing wheel 52 rotates again until the packing groove 521 communicates with the packing tube 93. The electromagnet 41 of the transfer mechanism 4 is energized, and the electromagnet 41 moves under the drive of the lead screw 42. Under the adsorption force of the magnet and the electromagnet 41, the magnet moves along the furnace chamber 22 to a specific position. The vacuum tube furnace is a multi-temperature zone vacuum tube furnace, which can realize thermal diffusion of multiple magnets under different conditions simultaneously.

[0062] Example 6

[0063] AsFigure 3-8 As shown in Figure 3-8 , a vacuum tube furnace includes a control box 1. Above the control box 1 is connected a furnace body 2. Above the furnace body 2 is connected a furnace cover 3. Inside the furnace body 2 is fixedly connected a furnace rack. In the middle of the furnace rack is provided a tube slot, on which a furnace chamber 22 is placed. At both ends of the furnace chamber 22 are respectively connected a closing mechanism 9. The closing mechanism 9 includes a fixed flange 91 fixedly connected to the furnace chamber 22. The fixed flange 91 is connected to a sealing flange 92. The other end of the sealing flange 92 is connected to a stuffing mechanism 5. On the side of the sealing flange 92 is connected a pressure gauge 73. The stuffing mechanism 5 includes a stuffing tube 93 communicating with the sealing flange 92. The end of the stuffing tube 93 is connected to a stuffing cylinder 51. Inside the stuffing cylinder 51 is rotatably connected a stuffing wheel 52. On the stuffing wheel 52 are provided stuffing grooves 521. On the side of the stuffing cylinder 51 are respectively connected an exhaust mechanism 6, an inflation mechanism 7, and a cooling mechanism 8. A transfer mechanism 4 is provided on the side of the furnace chamber 22.

[0064] The stuffing cylinder 51 is a hollow cylinder with an opening on the side. The outer part of the stuffing wheel 52 fits against the inner wall of the stuffing cylinder 51. The stuffing groove 521 is a cylindrical groove with the same inner diameter as the stuffing tube 93. The stuffing groove 521 communicates with the side of the stuffing wheel 52.

[0065] The transfer mechanism 4 includes a chute 21 arranged along the direction parallel to the axis of the furnace chamber 22 and close to the furnace chamber 22. Inside the chute 21 is provided an electromagnet 41. The electromagnet 41 is threadedly connected to a lead screw 42.

[0066] The exhaust mechanism 6 includes an exhaust cylinder 62 communicating with one end of the stuffing cylinder 51. The other end of the stuffing cylinder 51 is connected with a gas guide tube 61 aligned with the exhaust cylinder 62. Check valves are respectively connected to the outer ends of the exhaust cylinder 62 and the gas guide tube 61.

[0067] The inflation mechanism 7 includes an inflation tube 71 communicating with one end of the stuffing cylinder 51. The end of the inflation tube 71 is connected with an inflation valve. At the position aligned with the inflation tube 71 at the other end of the stuffing cylinder 51 is connected a pressure measuring tube 74. A pressure gauge 73 is connected to the pressure measuring tube 74. The other end of the pressure gauge 73 communicates with the stuffing tube 93.

[0068] The cooling mechanism 8 includes a cooling water pipe 82 connected to one end of the stuffing cylinder 51. The cooling water pipe 82 is aligned with a cooling flow channel 522 passing through the stuffing wheel 52. At the other end of the stuffing cylinder 51 is provided a drain port 81 aligned with the cooling flow channel 522.

[0069] In the filler, the magnet after magnetron sputtering enters the corresponding filler groove 521 through the filler port 511 on the side of the filler cylinder 51. When the filler wheel 52 rotates to communicate with the exhaust mechanism 6, the gas guide pipe 61 communicates with the inert gas storage tank. By opening the valve, inert gas can enter the filler groove 521. The inert gas passes through the filler groove 521, squeezes the internal air and carries a certain amount of air out from one end of the exhaust cylinder 62. In the case of continuously introducing inert gas, the air in the filler groove 521 can be basically expelled, avoiding the influence on the magnet performance due to the oxidation of the magnet surface coating during the thermal diffusion process;

[0070] After that, the filler wheel 52 rotates to communicate with the gas filling mechanism 7. The gas filling pipe 71 in the gas filling mechanism 7 is connected to the inert gas tank through the air supply and exhaust device in the prior art. At this time, one end of the pressure measuring pipe 74 communicates with the filler groove 521, and the other end communicates with the inside of the furnace chamber 22 connected by the fixed flange 91 through the connecting pipe 72. When the internal pressure of the filler groove 521 is high, the internal gas is discharged. When the internal pressure of the filler groove 521 is lower than the pressure in the furnace chamber 22, inert gas is supplemented into it. When the internal pressure of the filler groove 521 is the same as the internal pressure of the furnace chamber 22, the pointer of the pressure gauge 73 points to indicate that the pressures at both ends are balanced. After that, the filler wheel 52 can be controlled to rotate so that the filler groove 521 carrying the magnet communicates with the filler pipe 93, and the internal pressure of the furnace chamber 22 is kept stable after the communication, enabling the thermal diffusion to proceed stably, and it is possible to fill the material at any time, so that magnets with different heating times can be subjected to thermal diffusion treatment under the same conditions in the same vacuum tube furnace. Compared with the method of heating one by one, it saves more time.

[0071] When moving the magnet in the filler groove 521, the electromagnet 41 is energized to make it magnetic. The electromagnet 41 is threadedly connected to the lead screw 42 connected to the transfer motor 43. When the lead screw 42 rotates, the electromagnet 41 can axially move relative to the lead screw 42. Under the adsorption force of the electromagnet 41, the magnet in the filler groove 521 can move to the characteristic position of the specific temperature zone in the furnace chamber 22, realizing the thermal diffusion treatment of different magnets at different temperature conditions simultaneously.

[0072] After the heating of an individual magnet is completed, the electromagnet 41 in the transfer mechanism 4 moves to this position under the control of the transfer motor 43. Then, the electromagnet 41 is energized to adsorb the magnet and moves it to the filling groove 521 on the filling wheel 52 that is aligned with the filling pipe 93. After that, the filling wheel 52 rotates until the cooling flow channel 522 on the side of the filling groove 521 is communicated with the cooling water pipe 82. By opening the valve connected to the cooling water pipe 82, cooling water flows through the cooling water pipe 82 and is discharged from the drain port 81, so as to rapidly cool the magnet in the filling groove 521 through heat conduction. During this cooling process, the heat-treated magnet remains in the closed filling groove 521, avoiding reactions caused by contact between its surface and air or the cooling medium due to overheating, which may affect its surface anti-corrosion performance.

[0073] The above vacuum tube furnace is used for the study of the surface heat treatment conditions of magnets to determine the optimal heat treatment conditions, such as air pressure, temperature, and time. It can add additional magnets during the heat treatment process of a magnet in the furnace chamber 22, and the addition can be carried out without changing the internal environmental conditions of the furnace chamber 22, greatly shortening the experimental time.

Claims

1. Vacuum tube furnace, characterized in that: It includes a control box, with a furnace body connected above the control box, a furnace cover connected above the furnace body, a furnace rack fixedly connected inside the furnace body, a pipe groove arranged in the middle of the furnace rack, a furnace cavity placed on the pipe groove, and both ends of the furnace cavity are respectively connected to a closing mechanism. The closing mechanism includes a fixed flange fixedly connected to the furnace cavity, the fixed flange is connected to a sealing flange, the other end of the sealing flange is connected to a packing mechanism, and a pressure gauge is connected to the side of the sealing flange; The packing mechanism includes a packing pipe communicated with the sealing flange, the end of the packing pipe is connected to a packing cylinder, a packing wheel is rotatably connected inside the packing cylinder, packing grooves are arranged on the packing wheel, and an exhaust mechanism, an inflation mechanism, and a cooling mechanism are respectively connected to the side of the packing cylinder. A transfer mechanism is arranged on the side of the furnace cavity; The packing cylinder is a hollow cylindrical shape with an opening on the side, the outer part of the packing wheel fits with the inner wall of the packing cylinder, the packing groove is a cylindrical groove with the same inner diameter as the packing pipe, and the packing groove communicates with the side of the packing wheel; The transfer mechanism includes a chute arranged along the direction parallel to the axis of the furnace cavity and close to the furnace cavity, an electromagnet is arranged in the chute, and the electromagnet is threadedly connected to a lead screw.

2. The vacuum tube furnace according to claim 1, characterized in that: The exhaust mechanism includes an exhaust cylinder communicated with one end of the packing cylinder, a guide pipe aligned with the exhaust cylinder is connected to the other end of the packing cylinder, and check valves are respectively connected to the outer ends of the exhaust cylinder and the guide pipe.

3. The vacuum tube furnace according to claim 1, characterized in that: The inflation mechanism includes an inflation pipe communicated with one end of the packing cylinder, an inflation valve is connected to the end of the inflation pipe, a pressure measuring pipe is connected to the position aligned with the inflation pipe at the other end of the packing cylinder, a pressure gauge is connected to the pressure measuring pipe, and the other end of the pressure gauge is communicated with the packing pipe.

4. The vacuum tube furnace according to claim 1, characterized in that: The cooling mechanism includes a cooling water pipe connected to one end of the packing cylinder, the cooling water pipe is aligned with a cooling flow channel passing through the packing wheel, and a drain port aligned with the cooling flow channel is arranged at the other end of the packing cylinder.

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