Vacuum molybdenum wire sintering furnace

Abstract

The invention relates to the field of sintering furnaces, in particular to a vacuum molybdenum wire sintering furnace which comprises a furnace frame, a lifting mechanism is arranged on the furnace frame, a furnace bottom cover is fixed to the lifting mechanism, a furnace body is detachably connected to the furnace bottom cover, and a first reflecting screen, a first molybdenum wire heating body and a material table are sequentially fixed to the furnace bottom cover from bottom to top. The supporting pipe comprises a longitudinal supporting section and a transverse supporting section, the tail end of the longitudinal supporting section is communicated with an air outlet gathering pipe, and the tail end of the transverse supporting section is communicated with an air inlet gathering pipe. According to the molybdenum wire sintering furnace, due to the arrangement of the supporting pipe, a good supporting effect on a metal sheet is greatly improved, meanwhile, a good preheating effect on hydrogen can be achieved in the process that the hydrogen passes through the supporting pipe, and the stability of the temperature in the furnace can be guaranteed after the hydrogen enters the furnace after being preheated; and therefore, the sintering effect and efficiency of the materials are improved, and meanwhile, the effect of saving energy is achieved.

Description

Technical Field

[0001] The present invention relates to the field of sintering furnaces, and particularly to a vacuum molybdenum wire sintering furnace. Background Art

[0002] A vacuum molybdenum wire sintering furnace is a device for sintering materials under vacuum or protective atmosphere conditions. It has a vertical structure and is suitable for annealing, brazing, sintering, and degassing of metal materials under high vacuum and high temperature conditions. It is also suitable for dehydroxylation treatment of quartz materials.

[0003] A reflection screen is often provided in the molybdenum wire sintering furnace for heat preservation and insulation. For example, the patent with the application number CN201320754104.2 discloses a high-temperature hydrogen sintering furnace. Through the setting of the reflection screen, the high-temperature hydrogen sintering furnace has the effects of good heat insulation, effectively reducing heat loss, fast furnace heating speed, high thermal efficiency, and improving furnace temperature. However, the reflection screen still has the following drawbacks during use: 1) Since the reflection screen is composed of multiple layers of metal sheets and each layer of metal sheet is very thin, for the overall reflection screen, it is prone to deformation and has poor support effect; 2) The upper reflection screen and the side reflection screen of the reflection screen are connected together by a flange. In this connection method, heat will still be lost from the gap between the upper reflection screen and the side reflection screen, affecting the heat preservation effect.

[0004] During the sintering process of a vertical molybdenum wire sintering furnace, it is often necessary to introduce slightly positively pressurized flowing hydrogen into the furnace to reduce the oxides in the furnace. The common method of introducing hydrogen is to introduce it from the top of the sintering furnace and then lead it out from the bottom, and connect an igniter to burn the excess hydrogen. However, this method of introducing hydrogen often has the following drawbacks: 1) Since hydrogen is relatively light, when hydrogen is introduced from the top of the sintering furnace, it often accumulates in the upper part of the sintering furnace and slowly spreads downward as hydrogen is introduced until the entire sintering furnace is filled. This causes the newly introduced hydrogen to always accumulate in the upper part of the sintering furnace, resulting in the newly introduced hydrogen being unable to fully react with the oxides in the furnace in a timely and comprehensive manner, leading to poor reduction efficiency and effect; 2) When external hydrogen is directly introduced into the furnace, it will absorb a large amount of heat in the furnace instantly, which has an adverse effect on sintering and wastes a lot of thermal energy.

[0005] In summary, there is an urgent need for a molybdenum wire sintering furnace with good reflection screen support effect, good heat preservation effect, and at the same time, it can improve the reduction efficiency and effect and save energy when introducing reducing atmosphere hydrogen. Summary of the Invention

[0006] (I) Technical Problems to be Solved

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a vacuum molybdenum wire sintering furnace, which solves the problems existing in the prior art. Through the setting of the support tube, the molybdenum wire sintering furnace not only plays a good supporting role for the metal sheet, effectively preventing the deformation of the thin metal sheet and improving the overall stability of the second reflector screen, but also can play a good preheating role for hydrogen when hydrogen passes through the support tube. After the hydrogen is preheated and then enters the furnace, it can ensure the stability of the furnace temperature, thereby improving the sintering effect and efficiency of the material, and at the same time achieving the effect of saving energy.

[0008] (II) Technical Solution

[0009] To achieve the above object, the present invention provides the following technical solution: A vacuum molybdenum wire sintering furnace includes a furnace frame, on which a lifting mechanism is provided. A furnace bottom cover is fixed on the lifting mechanism, and a furnace body is detachably connected to the furnace bottom cover. The furnace bottom cover is fixedly provided with a first reflector screen, a first molybdenum wire heating element, and a material table from bottom to top in sequence. The first reflector screen is connected to a second reflector screen in an openable and closable manner. A second molybdenum wire heating element is provided inside the second reflector screen. The second reflector screen is composed of several layers of metal sheets. Each layer of metal sheet is composed of an annular metal sheet and a cylindrical metal sheet fixed on the top of the annular metal sheet. A gap is left between adjacent layers of metal sheets, and several support tubes are fixed in the gap. The support tube includes a longitudinal support section and a transverse support section. The end of the longitudinal support section is communicated with an air outlet collecting pipe, and the end of the transverse support section is communicated with an air inlet collecting pipe. A first gas outlet is opened on the second reflector screen, and a second gas outlet is opened on the furnace body.

[0010] Preferably, four support tubes are evenly fixed in the gap, and the longitudinal support sections in several gaps form four columns.

[0011] Preferably, several groups of staggered plates are arranged in the longitudinal support section. Each group of staggered plates is composed of a first staggered plate and a second staggered plate. Both the first staggered plate and the second staggered plate are inclined obliquely downward from the fixed end to the free end.

[0012] Preferably, the innermost layer of metal sheet of the second reflector screen is a tungsten sheet, and the remaining metal sheets are molybdenum sheets.

[0013] Preferably, a third reflector screen is provided in the upper inner part of the second reflector screen, and the third reflector screen is fixed on the furnace body through a first temperature control thermocouple.

[0014] Preferably, a second temperature control thermocouple and a third temperature control thermocouple are fixedly penetrated through the furnace body. The inner end of the second temperature control thermocouple is connected to the outside of the second reflector screen, and the inner end of the third temperature control thermocouple is connected to the second molybdenum wire heating element. A fourth temperature control thermocouple is fixedly penetrated through the furnace bottom cover, and the inner end of the fourth temperature control thermocouple is fixed to the first molybdenum wire heating element.

[0015] Preferably, the lifting mechanism includes a motor. The motor is connected to a transmission rod through a pair of bevel gears. Both ends of the transmission rod are connected to lead screws through a pair of bevel gears. A nut seat matching the lead screw is arranged on the lead screw. A lifting plate is fixed between the two nut seats. The furnace bottom cover is fixed to the lifting plate through a plurality of fixing seats.

[0016] Preferably, the first molybdenum wire heating element is formed by a plurality of first molybdenum wires in a bent and circuitous shape. The plurality of first molybdenum wires are fixed by a plurality of first fixing members.

[0017] Preferably, the second molybdenum wire heating element is arranged in a ring shape and is formed by a plurality of second molybdenum wires in a bent and circuitous shape. The plurality of second molybdenum wires are fixed by a plurality of second fixing members.

[0018] Preferably, the furnace body is arranged in a double-layer water-cooled sandwich structure.

[0019] (III) Beneficial effects

[0020] 1. In the present invention, the metal sheets forming the second reflecting screen are integrally formed in the form of annular metal sheets and cylindrical metal sheets. On the one hand, the sealing performance is greatly improved, thereby enhancing the heat insulation effect and saving energy. On the other hand, the installation is also greatly facilitated, and the stability of the metal sheets is also improved to a certain extent.

[0021] 2. The present invention provides good support for the metal sheet through the setting of the support tubes, effectively preventing the deformation of the thin metal sheet and enhancing the overall stability of the second reflection screen. At the same time, after connecting and fixing the metal sheet through the support tubes, there is no need for additional fixed connection between the metal sheets. In the prior art, a large number of fixing parts penetrate through all layers of the metal sheets to connect and fix all the metal sheets. This method of fixing and connecting the metal sheets through the support tubes reduces the damage to the second reflection screen and improves the heat preservation effect. In addition, the support tubes are also the pipelines for hydrogen to enter. Compared with the method of directly introducing hydrogen from the top of the sintering furnace in the prior art, the method of introducing hydrogen into the furnace after passing through the support tubes has the following advantages: 1) The process of hydrogen passing through the support tubes can preheat the hydrogen well. After the hydrogen is preheated and then enters the furnace, it can ensure the stability of the furnace temperature, thereby improving the sintering effect and efficiency of the materials, and also achieving the effect of saving energy; 2) After passing through the support tubes, hydrogen enters the space enclosed by the first reflection screen and the second reflection screen through the gas outlet collecting pipe. Hydrogen enters from the bottom of this space, then rises upward, and finally is led out from the first gas outlet. Since hydrogen is very light, when it enters from the lower end, it will have an upward movement process. This process from bottom to top can make hydrogen fully and comprehensively contact with the oxides in this space, thereby greatly improving the efficiency and effect of the reduction reaction; 3) Hydrogen enters from the bottom, so that the hydrogen entering the space enclosed by the first reflection screen and the second reflection screen always has an upward pushing force on the gas in this space, making it easier for the gas in the upper part of this space to be led out through the first gas outlet and ensuring the fluidity of hydrogen in this space; 4) The reduction reaction mainly occurs in the space enclosed by the first reflection screen and the second reflection screen. Compared with the method of introducing hydrogen into the entire furnace body in the prior art, this greatly reduces the reaction space, not only saving resources such as hydrogen, but also improving the efficiency and effect of the reduction reaction.

[0022] 3. During the process of furnace washing after the sintering of the present invention is completed, the introduction of two-way nitrogen not only safely and efficiently removes the remaining hydrogen in the furnace, but also achieves the effect of quickly cooling the furnace.

[0023] 4. The present invention evenly distributes the support tubes into four columns in the gap. In this way, each column of support tubes forms a concentrated support area, which not only improves the support effect on the second reflection screen, but also each column of support tubes forms a concentrated heat storage area. In this way, when hydrogen passes through the support tubes, it can improve the heating effect and efficiency of hydrogen, and ultimately improve the sintering effect and efficiency of the materials.

[0024] 5. By arranging staggered plates in the longitudinal support section, the present invention enhances the overall heat storage capacity of the longitudinal support section on the one hand, thereby enhancing the heating effect on hydrogen. On the other hand, the staggered plates can play a good role in mixing the hydrogen flow, making the heating of hydrogen more comprehensive and uniform. In addition, the time of hydrogen in the longitudinal support section is extended, further improving the heating effect on hydrogen.

[0025] 6. The present invention sets the metal sheet to be composed of a tungsten sheet and a molybdenum sheet. In this way, the tungsten sheet and the molybdenum sheet can efficiently reflect heat during the sintering process, reduce heat loss, save energy, and at the same time play a good heat preservation role. The innermost metal sheet is set as a tungsten sheet because the innermost metal sheet is closest to the second molybdenum wire heating body, and the high temperature resistance, hardness, and anti-deformation ability of the tungsten sheet are higher than those of the molybdenum sheet, thereby improving the overall stability and service life of the second reflection screen. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the whole of the present invention.

[0027] Figure 2 It is a cross-sectional view of the second reflection screen and the support tube of the present invention.

[0028] Figure 3 It is a cross-sectional view of the first reflection screen, the second reflection screen, the support tube, the air outlet collecting pipe, and the air inlet collecting pipe of the present invention.

[0029] Figure 4 It is a schematic diagram of the annular metal sheet and the cylindrical metal sheet of the present invention.

[0030] Figure 5 It is a schematic diagram of the support tube of the present invention.

[0031] Figure 6 It is a schematic diagram of the longitudinal support section and the staggered plates of the present invention.

[0032] Figure 7 It is a schematic diagram of the longitudinal support section, the first staggered plate, and the second staggered plate of the present invention.

[0033] Figure 8 It is a cross-sectional view of the second reflection screen and the support tube of the present invention.

[0034] Figure 9 It is a schematic diagram of the whole of the present invention.

[0035] Figure 10 It is a top view of the present invention after removing the furnace body top plate, the cylindrical metal sheet, and the third reflection screen.

[0036] Figure 11 It is a schematic diagram of the first molybdenum wire heating body of the present invention.

[0037] Figure 12 This is a cross-sectional view of the second molybdenum wire heating element and the second reflector screen of the present invention.

[0038] In the figure: 1 - furnace frame, 2 - lifting mechanism, 3 - furnace bottom cover, 4 - furnace body, 5 - first reflector screen, 6 - first molybdenum wire heating element, 7 - material table, 8 - second reflector screen, 9 - second molybdenum wire heating element, 10 - metal sheet, 11 - annular metal sheet, 12 - cylindrical metal sheet, 13 - gap, 14 - support tube, 15 - longitudinal support section, 16 - transverse support section, 17 - gas outlet manifold, 18 - gas inlet manifold, 19 - first gas outlet, 20 - second gas outlet, 21 - igniter, 22 - staggered plate, 23 - first staggered plate, 24 - second staggered plate, 25 - tungsten sheet, 26 - molybdenum sheet, 27 - third reflector screen, 28 - first temperature control thermocouple, 29 - second temperature control thermocouple, 30 - third temperature control thermocouple, 31 - fourth temperature control thermocouple, 32 - lead screw, 33 - nut seat, 34 - lifting plate, 35 - fixed seat, 36 - first molybdenum wire, 37 - first fixing member, 38 - second molybdenum wire, 39 - second fixing member, 40 - third fixing member. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the accompanying Figures 1-12 drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] The present invention provides a technical solution: a vacuum molybdenum wire sintering furnace, including a furnace frame 1, on which a lifting mechanism 2 is provided, a furnace bottom cover 3 is fixed on the lifting mechanism 2, a furnace body 4 is detachably connected to the furnace bottom cover 3, a first reflection screen 5, a first molybdenum wire heating element 6 and a material platform 7 are successively fixed on the furnace bottom cover 3 from bottom to top, the first reflection screen 5 is connected to a second reflection screen 8 in an openable and closable manner, a second molybdenum wire heating element 9 is provided inside the second reflection screen 8, the second reflection screen 8 is composed of several layers of metal sheets 10, each layer of metal sheet 10 is composed of an annular metal sheet 11 and a cylindrical metal sheet 12 fixed on the top of the annular metal sheet 11, a gap 13 is left between adjacent layers of metal sheets 10, several support pipes 14 are fixed in the gap 13, the support pipes 14 include a longitudinal support section 15 and a transverse support section 16, an air outlet collecting pipe 17 is communicated with the end of the longitudinal support section 15, an air inlet collecting pipe 18 is communicated with the end of the transverse support section 16, a first gas outlet 19 is opened on the second reflection screen 8, and a second gas outlet 20 is opened on the furnace body 4. During operation, first, the lifting mechanism 2 lowers the furnace bottom cover 3 to the bottom of the furnace frame 1, then the material is placed on the material platform 7, and then the lifting mechanism 2 raises the furnace bottom cover 3 until the furnace bottom cover 3 is closed with the furnace body 4. After the furnace bottom cover 3 and the furnace body 4 are closed, they can be locked by locking parts such as screws and nuts. Then, the inside of the furnace body is evacuated by a vacuum pumping system. Then, the first molybdenum wire heating element 6 and the second molybdenum wire heating element 9 are started to heat and sinter the material. During the sintering process, a reducing atmosphere hydrogen is filled into the air inlet collecting pipe 18 through an atmosphere filling system. The atmosphere filling system is communicated with the air inlet collecting pipe 18. The hydrogen enters the transverse support section 16 through the air inlet collecting pipe 18, then enters the longitudinal support section 15, and then enters the space enclosed by the first reflection screen 5 and the second reflection screen 8 from the air outlet collecting pipe 17, and undergoes a reduction reaction with the oxides therein. Then, it enters the space between the first reflection screen 5, the second reflection screen 8 and the furnace body 4 from the first gas outlet 19, and finally is led out from the second gas outlet 20. Just keep continuously passing hydrogen into the furnace until the sintering is completed. The furnace body 4 is fixedly connected to the furnace frame 1 through fixing parts. The second gas outlet 20 can be connected to an igniter 21, so that the gas led out from the furnace is burned at the igniter 21. The igniter 21 can be a silicon nitride igniter. Since the hydrogen in the furnace needs to maintain fluidity, that is, hydrogen needs to be continuously passed into the furnace, and the furnace needs to maintain a slightly positive pressure state, an automatic pressure relief valve can be connected to the outer ends of both the first gas outlet 19 and the second gas outlet 20, so that the pressure inside the furnace can be automatically adjusted to keep the furnace always in the required slightly positive pressure state.After sintering, there is still a full furnace of hydrogen left. If this hydrogen is not disposed of in a timely manner, it is very dangerous and there is a high risk of explosion. It is also not safe to extract the hydrogen by means of vacuum pumping, as there are significant risks. Therefore, the furnace is purged by introducing a sufficient amount of nitrogen into the furnace to drive the hydrogen out of the furnace. The specific purging method after sintering is as follows: Nitrogen is introduced into the intake manifold 18 through the atmosphere charging system. The nitrogen is introduced in two paths. One path of nitrogen enters the space enclosed by the first reflection screen 5 and the second reflection screen 8 through the horizontal support section 16, the vertical support section 15, and the outlet manifold 17, driving the hydrogen in this space upward and entering the upper space between the first reflection screen 5, the second reflection screen 8, and the furnace body 4 through the first gas outlet 19. The other path of nitrogen is introduced from the bottom of the furnace body 4. There is a nitrogen inlet opened at the bottom of the furnace body 4, and this nitrogen inlet is connected to the atmosphere charging system. By introducing nitrogen, the hydrogen in the first reflection screen 5, the second reflection screen 8, and the furnace body 4 is driven upward, and finally the hydrogen driven to the upper part passes through the second gas outlet 20 to the igniter 21 for combustion. The vacuum pumping system and the atmosphere charging system are conventional technical means in the art, and their specific structures will not be elaborated here. The first reflection screen 5 is also composed of several cylindrical metal sheets, which exactly cover the opening at the bottom of the second reflection screen 8, making the space enclosed by the first reflection screen 5 and the second reflection screen 8 a closed space. In the present invention, the metal sheet 10 constituting the second reflection screen 8 is arranged in a manner of integrally forming a ring-shaped metal sheet 11 and a cylindrical metal sheet 12. Compared with the way in the comparative document CN201320754104.2 where the upper reflection screen and the side reflection screen are connected and fixed by flanges, on the one hand, the sealing performance is greatly improved, thus enhancing the heat insulation effect and saving energy, and on the other hand, the installation is also greatly facilitated, and at the same time, the stability of the metal sheet 10 is also improved to a certain extent.The present invention provides a good supporting effect on the metal sheet 10 through the arrangement of the support tube 14, effectively preventing the deformation of the thin metal sheet 10 and improving the overall stability of the second reflective screen 8. At the same time, after connecting and fixing the metal sheet 10 through the support tube 14, there is no need for additional fixed connection between the metal sheets 10. In the prior art, a large number of fixing parts penetrate through all layers of the metal sheet 10 to connect and fix all the metal sheets. This method of fixing and connecting the metal sheet 10 through the support tube 14 reduces the damage to the second reflective screen 8 and improves the heat preservation effect. In addition, the support tube 14 is also a pipeline for hydrogen to enter. Compared with the prior art method of directly introducing hydrogen from the top of the sintering furnace, the hydrogen enters the furnace after passing through the support tube 14, which has the following advantages: 1) The process of hydrogen passing through the support tube 14 can preheat the hydrogen well. After the hydrogen is preheated and then enters the furnace, it can ensure the stability of the furnace temperature, thereby improving the sintering effect and efficiency of the material, and also achieving the effect of saving energy; 2) After passing through the support tube 14, the hydrogen enters the space enclosed by the first reflective screen 5 and the second reflective screen 8 through the gas outlet collecting pipe 17. The hydrogen enters from the bottom of this space, then rises upward, and finally is led out from the first gas outlet 19. Since hydrogen is very light, when it enters from the lower end, it will have an upward process. This process from bottom to top can make the hydrogen fully and comprehensively contact with the oxides in this space, thereby greatly improving the efficiency and effect of the reduction reaction; 3) The hydrogen enters from the bottom, which makes the hydrogen entering the space enclosed by the first reflective screen 5 and the second reflective screen 8 always have an upward pushing force on the gas in this space, making it easier for the gas in the upper part of this space to be led out through the first gas outlet 19 and ensuring the fluidity of hydrogen in this space; 4) The reduction reaction mainly occurs in the space enclosed by the first reflective screen 5 and the second reflective screen 8. Compared with the prior art of introducing hydrogen into the entire furnace body, this greatly reduces the reaction space, not only saving resources such as hydrogen, but also improving the efficiency and effect of the reduction reaction. During the furnace washing process after the sintering of the present invention is completed, the introduction of two-way nitrogen not only safely and efficiently removes the remaining hydrogen in the furnace, but also achieves the effect of quickly cooling the furnace.

[0041] Four support tubes 14 are uniformly fixed in the gap 13. The longitudinal support sections 15 in a number of gaps 13 form four columns, and the arrangement and distribution of the longitudinal support sections 15 are as Figure 2 shown. This setting evenly divides the second reflective screen 8 into four areas through the support tubes 14. Each column of support tubes 14 forms a concentrated support area, which not only improves the support effect on the second reflective screen 8, but also each column of support tubes 14 forms a concentrated heat storage area. In this way, when hydrogen passes through the support tubes 14, it can improve the heating effect and efficiency of hydrogen, and ultimately improve the sintering effect and efficiency of the material. The material of the support tube 14 can be tungsten or molybdenum.

[0042] There are several groups of staggered plates 22 arranged inside the longitudinal support section 15. Each group of staggered plates 22 consists of a first staggered plate 23 and a second staggered plate 24. Both the first staggered plate 23 and the second staggered plate 24 are inclined obliquely downward from the fixed end to the free end. The material of the first staggered plate 23 and the second staggered plate 24 can be tungsten or molybdenum. On the one hand, the arrangement of the staggered plates 22 enhances the overall heat storage capacity of the longitudinal support section 15, thereby enhancing the heating effect on hydrogen. On the other hand, the staggered plates 22 can play a good role in mixing the hydrogen flow, making the heating of hydrogen more comprehensive and uniform. In addition, it prolongs the residence time of hydrogen in the longitudinal support section 15, further improving the heating effect on hydrogen.

[0043] The innermost metal sheet 10 of the second reflective screen 8 is a tungsten sheet 25, and the remaining metal sheets 10 are molybdenum sheets 26. The metal sheets 10 are arranged to be composed of tungsten sheets 25 and molybdenum sheets 26. In this way, the tungsten sheets 25 and molybdenum sheets 26 can efficiently reflect heat during the sintering process, reduce heat loss, save energy, and also play a good heat preservation role. The innermost metal sheet 10 is set as the tungsten sheet 25 because the innermost metal sheet is closest to the second molybdenum wire heating element 9, and the tungsten sheet has higher high-temperature resistance, hardness, and anti-deformation ability compared to the molybdenum sheet. The thickness of the tungsten sheet 25 is 0.5 mm, the thickness of the molybdenum sheet 26 closest to the tungsten sheet 25 is 0.3 mm, and the thickness of the remaining molybdenum sheets 26 is 0.2 mm. The thicknesses of the tungsten sheet 25 and the molybdenum sheets 26 should neither be too thick nor too thin. If they are too thick, the entire second reflective screen 8 will absorb relatively more heat during heating, resulting in relatively more heat storage, which will cause the overall temperature rise in the sintering furnace to be slow. Therefore, the thinner the tungsten sheet 25 and the molybdenum sheets 26 are, the better. However, when it is thin to a certain extent, the processing becomes more difficult, the processing cost is very high, and the support effect is poor and it is easy to crack. Therefore, the thickness of the tungsten sheet 25 is 0.5 mm, the thickness of the molybdenum sheet 26 closest to the tungsten sheet 25 is 0.3 mm, and the thickness of the remaining molybdenum sheets 26 is 0.2 mm. This thickness is the best after overall consideration.

[0044] A third reflective screen 27 is arranged at the upper inner part of the second reflective screen 8. The third reflective screen 27 is fixed on the furnace body 4 through the first temperature control thermocouple 28. Since the first molybdenum wire heating element 6 is arranged near the bottom of the furnace body 4, the temperature in this area is higher than the temperature at the top of the furnace body 4. Therefore, the third reflective screen 27 is arranged to enhance the heat preservation effect at the top of the furnace body 4, ensure the temperature uniformity of the upper and lower two areas of the furnace body 4, and thus ensure the final sintering effect. The temperature of the third reflective screen 27 is monitored in real time through the first temperature control thermocouple 28.

[0045] A second temperature control thermocouple 29 and a third temperature control thermocouple 30 are fixedly penetrated through the furnace body 4. The inner end of the second temperature control thermocouple 29 is connected to the outer side of the second reflection screen 8, and the inner end of the third temperature control thermocouple 30 is connected to the second molybdenum wire heating element 9. A fourth temperature control thermocouple 31 is fixedly penetrated through the furnace bottom cover 3, and the inner end of the fourth temperature control thermocouple 31 is fixed to the first molybdenum wire heating element 6. Among them, through the setting of the second temperature control thermocouple 29, the outer side of the second reflection screen 8 is monitored for the temperature in real time. Through the setting of the third temperature control thermocouple 30, the second molybdenum wire heating element 9 is monitored for the temperature in real time. Through the fourth temperature control thermocouple 31, the first molybdenum wire heating element 6 is monitored for the temperature in real time.

[0046] The lifting mechanism 2 includes a motor. The motor is connected to a transmission rod through a pair of bevel gears. Both ends of the transmission rod are connected to a lead screw 32 through a pair of bevel gears. A nut seat 33 matching the lead screw 32 is provided on the lead screw 32. An elevator plate 34 is fixed between the two nut seats 33. The elevator plate 34 is fixed with the furnace bottom cover 3 through a plurality of fixing seats 35. Among them, the lifting mechanism 2 belongs to the prior art. Specifically, the motor drives the transmission rod to rotate, and then drives the two lead screws 32 to rotate synchronously, and then drives the two nut seats 33 to move up and down synchronously along the lead screws 32, and then drives the elevator plate 34 fixed between the two nut seats 33 to rise or fall, and finally drives the furnace bottom cover 3 to close or separate from the furnace body 4.

[0047] The first molybdenum wire heating element 6 is formed by aggregating a plurality of first molybdenum wires 36 in a bent and circuitous shape. A plurality of first fixing members 37 are used to fix between the plurality of first molybdenum wires 36. Among them, the first molybdenum wires 36 are set in a bent and circuitous shape, so as to improve the heating efficiency and effect.

[0048] The second molybdenum wire heating element 9 is set in a ring shape. It is formed by aggregating a plurality of second molybdenum wires 38 in a bent and circuitous shape. A plurality of second fixing members 39 are used to fix between the plurality of second molybdenum wires 38. Among them, the second molybdenum wires 38 are set in a bent and circuitous shape, so as to improve the heating efficiency and effect on the material. Among them, the second molybdenum wire heating element 9 is fixed to the second reflection screen 8 through a plurality of third fixing members 40.

[0049] The furnace body 4 is set in a double-layer water-cooled sandwich structure. The furnace body 4 is set in a double-layer water-cooled sandwich structure. The cooling water in the sandwich is circulated through an external water cooler. Through this setting, the furnace body 4 made of stainless steel is well cooled. On the one hand, it prevents the stainless steel furnace body 4 from being damaged due to excessive temperature. On the other hand, it prevents workers from being accidentally scalded by the furnace body 4. In addition, this double-layer water-cooled sandwich structure also plays a good role in dissipating heat and cooling the finished product after hot pressing.

[0050] Working principle: During operation, first, the lifting mechanism 2 lowers the furnace bottom cover 3 to the bottom of the furnace frame 1. Then, materials are placed on the material table 7. After that, the lifting mechanism 2 raises the furnace bottom cover 3 until the furnace bottom cover 3 closes with the furnace body 4. After the furnace bottom cover 3 and the furnace body 4 are closed, they can be locked by locking parts such as screws and nuts. Then, the inside of the furnace body is evacuated by the vacuum pumping system. After that, the first molybdenum wire heating element 6 and the second molybdenum wire heating element 9 are started to heat and sinter the materials. During the sintering process, a reducing atmosphere of hydrogen is filled into the intake manifold 18 through the atmosphere filling system. The atmosphere filling system is connected to the intake manifold 18. Hydrogen enters the transverse support section 16 through the intake manifold 18, then enters the longitudinal support section 15, and then enters the space enclosed by the first reflection screen 5 and the second reflection screen 8 from the outlet manifold 17, and undergoes a reduction reaction with the oxides therein. Then, it enters the space between the first reflection screen 5, the second reflection screen 8 and the furnace body 4 from the first gas outlet 19, and finally is led out from the second gas outlet 20. Just keep passing hydrogen into the furnace like this until the sintering is completed. The second gas outlet 20 can be connected to an igniter 21, so that the gas led out from the furnace is burned at the igniter 21. The igniter 21 can be a silicon nitride igniter 21. Since the hydrogen in the furnace needs to maintain fluidity, that is, hydrogen needs to be continuously passed into the furnace, and the furnace needs to maintain a slightly positive pressure state. Therefore, an automatic pressure relief valve can be connected to the outer ends of both the first gas outlet 19 and the second gas outlet 20, so that the pressure in the furnace can be automatically adjusted to keep the furnace always in the required slightly positive pressure state. After the sintering is completed, there is still a full furnace of hydrogen left. If these hydrogen gases are not disposed of in time, it is very dangerous and there is a high risk of explosion. If the hydrogen is pumped out by vacuum pumping, it is also not safe and there are great risks. Therefore, the furnace is washed by passing a sufficient amount of nitrogen into the furnace to drive the hydrogen out of the furnace. The specific furnace washing method after the sintering is completed is as follows: Nitrogen is filled into the intake manifold 18 through the atmosphere filling system. The nitrogen is filled in two paths. One path of nitrogen enters the space enclosed by the first reflection screen 5 and the second reflection screen 8 through the transverse support section 16, the longitudinal support section 15 and the outlet manifold 17, driving the hydrogen in this space upward and entering the upper space between the first reflection screen 5, the second reflection screen 8 and the furnace body 4 through the first gas outlet 19. The other path of nitrogen is introduced from the bottom of the furnace body 4. There is a nitrogen inlet opening at the bottom of the furnace body 4, and this nitrogen inlet opening is connected to the atmosphere filling system. By introducing nitrogen, the hydrogen in the first reflection screen 5, the second reflection screen 8 and the furnace body 4 is driven upward, and finally the hydrogen driven to the upper part is burned at the igniter 21 through the second gas outlet 20. The vacuum pumping system and the atmosphere filling system are conventional technical means in the field, and their specific structures will not be elaborated here. The first reflection screen 5 is also composed of several cylindrical metal sheets, which just cover the opening at the bottom of the second reflection screen 8, so that a closed space is formed between the first reflection screen 5 and the second reflection screen 8.In the present invention, the metal sheet 10 that constitutes the second reflection screen 8 is arranged to be integrally formed by an annular metal sheet 11 and a cylindrical metal sheet 12. Compared with the way in the comparative document CN201320754104.2 where the upper reflection screen and the side reflection screen are connected and fixed by flanges, on the one hand, the sealing performance is greatly improved, thus enhancing the heat insulation effect and saving energy. On the other hand, the installation is also greatly facilitated, and the stability of the metal sheet 10 is improved to a certain extent. In the present invention, the support tube 14 is provided to play a good supporting role for the metal sheet 10, effectively preventing the deformation of the thin metal sheet 10 and enhancing the overall stability of the second reflection screen 8. At the same time, after the metal sheet 10 is connected and fixed by the support tube 14, there is no need for additional fixed connection between the metal sheets 10. In the prior art, a large number of fixing parts penetrate all layers of the metal sheet 10 to connect and fix all the metal sheets. This way of fixing and connecting the metal sheet 10 by the support tube 14 reduces the damage to the second reflection screen 8 while improving the heat insulation effect. In addition, the support tube 14 is also a pipeline for hydrogen to enter. Compared with the way of directly introducing hydrogen from the top of the sintering furnace in the prior art, the hydrogen entering the furnace after passing through the support tube 14 has the following advantages: 1) The process of hydrogen passing through the support tube 14 can play a good preheating role for hydrogen. After the hydrogen is preheated and then enters the furnace, it can ensure the stability of the furnace temperature, thereby improving the sintering effect and efficiency of the materials, and also achieving the effect of saving energy; 2) After passing through the support tube 14, the hydrogen enters the space enclosed by the first reflection screen 5 and the second reflection screen 8 through the gas outlet collecting pipe 17. The hydrogen enters from the bottom of this space, then rises upward, and finally is led out from the first gas outlet 19. Since hydrogen is very light, when it enters from the lower end, it will have an upward process. This process from bottom to top can make the hydrogen fully and comprehensively contact with the oxides in this space, thereby greatly improving the efficiency and effect of the reduction reaction; 3) The hydrogen enters from the bottom, so that the hydrogen entering the space enclosed by the first reflection screen 5 and the second reflection screen 8 always has an upward pushing force on the gas in this space, making it easier for the gas in the upper part of this space to be led out through the first gas outlet 19 and ensuring the fluidity of hydrogen in this space; 4) The reduction reaction mainly occurs in the space enclosed by the first reflection screen 5 and the second reflection screen 8. Compared with introducing hydrogen into the entire furnace body in the prior art, the reaction space is greatly reduced. This not only saves resources such as hydrogen, but also improves the efficiency and effect of the reduction reaction. During the furnace washing process after the sintering in the present invention, by introducing two paths of nitrogen, not only the remaining hydrogen in the furnace is safely and efficiently removed, but also the effect of quickly cooling the furnace is achieved.

[0051] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A vacuum molybdenum wire sintering furnace, characterized in that: The invention comprises a furnace frame (1), wherein the furnace frame (1) is provided with a lifting mechanism (2), a furnace bottom cover (3) is fixed on the lifting mechanism (2), a furnace body (4) is detachably connected to the furnace bottom cover (3), a first reflection screen (5), a first molybdenum wire heating body (6) and a material table (7) are fixed to the furnace bottom cover (3) in sequence from bottom to top, the first reflection screen (5) is openably connected to a second reflection screen (8), a second molybdenum wire heating body (9) is provided on the inner side of the second reflection screen (8), and the second reflection screen (8) is composed of a plurality of layers of metal sheets (10), each layer of the metal sheets (10) is composed of an annular metal sheet (11) and The invention is composed of a cylindrical metal sheet (12) fixed on the top of the annular metal sheet (11), a gap (13) is left between two adjacent layers of the metal sheets (10), a plurality of support tubes (14) are fixed in the gap (13), the support tubes (14) include a longitudinal support section (15) and a transverse support section (16), the end of the longitudinal support section (15) is connected to a gas outlet manifold (17), the end of the transverse support section (16) is connected to a gas inlet manifold (18), the second reflection screen (8) is provided with a first gas outlet (19), and the furnace body (4) is provided with a second gas outlet (20).

2. A vacuum molybdenum wire sintering furnace according to claim 1, characterized in that: Four support tubes (14) are evenly fixed in the gap (13), and the longitudinal support sections (15) in a plurality of the gaps (13) form four rows.

3. A vacuum molybdenum wire sintering furnace according to claim 1, characterized in that: A plurality of groups of staggered plates (22) are arranged in the longitudinal support section (15), each group of the staggered plates (22) is composed of a first staggered plate (23) and a second staggered plate (24), and the first staggered plates (23) and the second staggered plates (24) are both inclined downward from the fixed end to the free end.

4. A vacuum molybdenum wire sintering furnace according to claim 1, characterized in that: The innermost metal sheet (10) of the second reflection screen (8) is a tungsten sheet (25), and the remaining metal sheets (10) are molybdenum sheets (26).

5. The vacuum molybdenum wire sintering furnace according to claim 1, characterized in that: A third reflecting screen (27) is provided at the inner upper portion of the second reflecting screen (8), and the third reflecting screen (27) is fixed to the furnace body (4) via a first temperature-controlling thermocouple (28).

6. A vacuum molybdenum wire sintering furnace according to claim 1, characterized in that: A second temperature-controlling thermocouple (29) and a third temperature-controlling thermocouple (30) are fixedly passed through the furnace body (4); the inner end of the second temperature-controlling thermocouple (29) is connected to the outer side of the second reflecting screen (8); the inner end of the third temperature-controlling thermocouple (30) is connected to the second molybdenum wire heating body (9); a fourth temperature-controlling thermocouple (31) is fixedly passed through the furnace bottom cover (3); the inner end of the fourth temperature-controlling thermocouple (31) is fixed to the first molybdenum wire heating body (6).

7. The vacuum molybdenum wire sintering furnace according to claim 1, characterized in that: The lifting mechanism (2) comprises a motor, the motor is connected to a transmission rod via a pair of bevel gears, both ends of the transmission rod are connected to a screw rod (32) via a pair of bevel gears, a nut seat (33) matching the screw rod (32) is provided on the screw rod (32), a lifting plate (34) is fixed between the two nut seats (33), and the lifting plate (34) is fixed to the furnace bottom cover (3) via a plurality of fixing seats (35).

8. The vacuum molybdenum wire sintering furnace according to claim 1, characterized in that: The first molybdenum wire heating body (6) is formed by a plurality of bent and circuitous first molybdenum wires (36), and the plurality of first molybdenum wires (36) are fixed by a plurality of first fixing members (37).

9. The vacuum molybdenum wire sintering furnace according to claim 1, characterized in that: The second molybdenum wire heating body (9) is arranged in a ring shape and is composed of a plurality of curved and circuitous second molybdenum wires (38), wherein the plurality of second molybdenum wires (38) are fixed by a plurality of second fixing members (39).

10. The vacuum molybdenum wire sintering furnace according to claim 1, characterized in that: The furnace body (4) is configured as a double-layer water-cooled sandwich structure.

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