CN110603417B - Vacuum degreasing sintering furnace and using method thereof - Google Patents
Vacuum degreasing sintering furnace and using method thereof Download PDFInfo
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- CN110603417B CN110603417B CN201880020622.7A CN201880020622A CN110603417B CN 110603417 B CN110603417 B CN 110603417B CN 201880020622 A CN201880020622 A CN 201880020622A CN 110603417 B CN110603417 B CN 110603417B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/003—Apparatus, e.g. furnaces
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/1003—Use of special medium during sintering, e.g. sintering aid
- B22F3/1007—Atmosphere
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/1017—Multiple heating or additional steps
- B22F3/1021—Removal of binder or filler
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B17/00—Furnaces of a kind not covered by any preceding group
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/10—Reduction of greenhouse gas [GHG] emissions
- Y02P10/143—Reduction of greenhouse gas [GHG] emissions of methane [CH4]
Abstract
The invention discloses a vacuum degreasing sintering furnace and a using method thereof, and relates to the technical field of special manufacturing equipment for powder metallurgy, powder ceramic sintering and the like.A graphite feed box (3) is provided with an inner air charging port (4) and an inner air pumping port (5), the inner air charging port (4) is communicated with an inner air charging pipe (6), the inner air pumping port (5) is communicated with an inner air pumping pipe (7), a furnace body (1) is provided with an outer air charging port (8) and an outer air pumping port (9), the outer air charging port (8) is communicated with an outer air charging pipe (10), and the outer air pumping port (9) is communicated with an outer air pumping pipe (11). The vacuum degreasing sintering furnace mainly fills the process gas into the graphite feed box (3), and fills the inert gas outside the graphite feed box (3) as an auxiliary, so that the atmosphere inside and outside the graphite feed box (3) is isolated, various impure atmospheres and pollutants outside the graphite feed box (3) are reduced from entering the graphite feed box (3) to influence the sintering of products, the product quality and the production speed are improved, the pollution degree in the furnace is reduced, the service life of the vacuum degreasing sintering furnace is prolonged, and the use of hydrogen during high-temperature sintering and the use of oxygen during low-temperature degreasing are made possible.
Description
Technical Field
The invention relates to the technical field of special manufacturing equipment for powder metallurgy, powder ceramic sintering and the like, in particular to a vacuum degreasing sintering furnace and a using method thereof.
Background
The graphite thermal field vacuum degreasing sintering furnace is used for degreasing and sintering metal powder blanks, main components in the furnace are made of carbon fibers and graphite, and the graphite is one of main materials of the vacuum sintering furnace due to the advantages of excellent conductivity, super heat resistance, high reliability, lightness, easiness in processing, long service life and the like, but has the following problems:
1. dust impact: graphite and carbon fiber are easy to generate dust, the graphite dust and the carbon fiber dust can be brought into a material box along with air flow and are attached to a product in the material box, defects are easy to generate on the surface of the product during sintering, and the carbon content in the product is increased, so that the performance of the product made of stainless steel such as 316, 304, 316L, 17-4PH and the like with higher requirements is reduced.
2. Influence of moisture: when the furnace door is opened, moisture in the air can enter the furnace and enter the carbon fiber heat insulation cylinder, the moisture can be changed into steam to escape at high temperature in vacuum, the moisture oxidizes the surface of a product, and the phenomena of slight yellowing and severe graying and bluing appear.
3. The influence of leakage: the leakage of the vacuum furnace is unavoidable, and only the leakage is controlled to a low level, and air enters from a position such as a furnace door and is easy to contact with a sintered product to affect the performance of the product. The leakage from different furnaces varies, causing differences in the products sintered in different furnaces.
4. Contamination effects of new substances: the ceramic plate (burning bearing plate) is an intermediary for placing products, and the products are directly burnt without the ceramic plate (such as PM and MIM products), so the ceramic plate (burning bearing plate) is a necessary burning bearing part for sintering. But the ceramic plate is directly contacted with the graphite plate, so that carbothermic reduction reaction can be generated to generate Al and Al2O3When the new substances are attached to the surface of the product, the upper cover of the material box is opened during processes such as vacuumizing or cooling in the furnace, the generated new substances can run to the outside of the material box and enter the carbon fiber heat insulation cylinder or attach to the inner wall of the furnace to pollute the heat insulation cylinder and then run into the material box in the next process operation link of the furnace, and the processes are circulated in such a way that the new substances can be deposited on the surface of the product when a certain amount of the new substances is reached, so that the surface of the product is poor and the performance of the product is influenced.
5. Effect of binder contamination: the vacuum environment is favorable for the gasification of the adhesive, but the adhesive is easy to diffuse, when degreasing, the adhesive can be separated from the product, becomes steam and diffuses, and part of the steam can leak to the outside of the bin and enter the carbon fiber heat insulation cylinder or be attached to the inner wall of the furnace to pollute the furnace. During the sintering process, the binder vapor is carried into the bin by the carrier gas to pollute the product and influence the size and performance of the product.
The furnace structure of the existing vacuum degreasing sintering furnace is shown in fig. 1 and fig. 2, a material box B1 is connected with an inner pumping pipe B2, an inner pumping pipe B2 is connected with a vacuum pump B3, during degreasing and sintering processes, process gas is filled into the furnace, the vacuum pump works, the pressure outside the material box is larger than the pressure inside the material box, the pressure difference promotes the gas to flow in a single direction, the gas outside the material box enters the material box from a gap between a material box door and a material box body, and the gas enters the material box, passes through the surface of a product and then enters the inner pumping pipe B2. The Chinese patent application with the publication number of CN103264163A and the publication date of 2013, 5 and 6 discloses a directional airflow device of a metal powder injection molding vacuum degreasing sintering furnace, wherein an air inlet device is arranged on a door plate, and when the pressure difference inside and outside a material box reaches a certain value, an air inlet valve is opened to enable airflow to enter from the door plate, flow through the surface of a product and enter an internal pumping pipe. In the prior art, the gas carries the atmosphere and contaminants from the space outside the bin into the bin and flows through the product. The atmosphere comprises leaked air, water deposited in the heat insulation carbon fiber heat insulation cylinder, carbon and other atmospheres; the pollutants include dust, alumina or silica and the like. The product in the bin is contaminated and defective, a high carbon atmosphere can carbonize the product, air can oxidize the product, and alumina or silica can deform the product and make the product uneven in size.
In addition, the problem that the use of process gas is limited exists, because the thermal conductivity of hydrogen is very good and is 7 times of that of nitrogen at room temperature, the product blank can be heated quickly and can react with high molecules to accelerate the decomposition of high molecular organic matters in the binder, and therefore, the hydrogen is often applied to the degreasing process of a sintering furnace to improve the degreasing rate. And because the diffusion rate of the hydrogen in metal is quite high and the reduction capability of the hydrogen to oxide is strong, the hydrogen is an ideal sintering process gas.
The purpose of using hydrogen in high-temperature sintering is that the hydrogen reacts with carbon to remove the carbon generated in the following steps:
1. when the graphite thermal field is used for high-temperature sintering, the carbon content exceeds the standard due to high overall carbon potential when the low-carbon stainless steel is sintered, for example, 316L, the carbon content is difficult to be below 0.04 percent when the graphite thermal field is used.
2. In the case of degreasing at low temperature, carbon remaining in a thermal field volatilizes to form free carbon during high-temperature sintering, and the free carbon causes carburization or partial carburization of the product.
3. When the metal powder is prepared, an oxide layer is formed on the surface, if the oxide layer is not removed, diffusion is hindered during sintering, so that the product cannot be compact, and carbon oxide can be reduced by using hydrogen.
However, hydrogen is limited in use in the sintering process of graphite thermal fields within the industry. Because the hydrogen and carbon react in the sensitive temperature area (1000-1200 ℃). The components in the existing vacuum degreasing sintering furnace are made of carbon regardless of a material box B1 or a heat insulation cylinder B5. Experiments show that hydrogen is introduced into the graphite rod at a gradually changing temperature, and the hydrogen and the graphite react with each other to consume a graphite piece, as shown in fig. 3. Therefore, hydrogen is not allowed to be introduced in the sintering process of the graphite thermal field in the prior art. And it is not feasible to introduce hydrogen into the furnace only outside the temperature sensitive zone. The heating material B4 (graphite electrode bar, graphite heating bar and graphite connecting sheet) is arranged on the outer ring of the bin to heat the bin B1, and the carbon fiber heat insulation cylinder B5 is arranged on the outer ring of the heating material B4 to keep the heat of the bin B1 from losing. The graphite upright post B8 is used for supporting a graphite bin B1, and an inner graphite pumping pipe B2 is used for connecting a vacuum pipeline system and the bin B1, so that the air flow direction is ensured. The outside of a bin B1 in the furnace is provided with a plurality of graphite pieces, and cooling water is filled in a jacket of a furnace body B7, so the temperature from the bin B1 to the inner wall (from inside to outside) of the furnace is different, wherein the temperature of a heating material B4 is the highest, the temperature of the outer wall of the bin B1 is raised through radiation, and the temperature of the bin is transmitted into the bin B1 on one hand and is transmitted to the graphite pieces such as a graphite upright post B8 and a graphite upper cover B9 on the other hand. The temperature of the inner wall of the heat insulation barrel B5 is higher, and the temperature of the outer wall is lower, so that the temperature of each component in the furnace is different. The thermocouple B6 monitors the temperature of the material box B1, when the temperature of the material box B1 is controlled to be outside the hydrogen reaction sensitive area, for example 1300 ℃, the temperature of the heating material B4 is higher than 1300 ℃, but the temperature of the graphite piece close to the heat insulation cylinder B5 is in the hydrogen reaction sensitive area, and the hydrogen reacts with the graphite piece in the temperature range, so that parts are lost.
The degreasing process is also important for the quality of products, and if degreasing is not clean, the size of the products is large during subsequent sintering, the surfaces of the products become grey, and the performance of the products does not reach the standard. In the prior art, the rejection rate is extremely high, and the solution only needs to prolong the degreasing time, so that the binder in the product is discharged as much as possible. At low temperature, the oxygen in the air reacts with the binder to accelerate the degreasing speed (the main component of the binder is macromolecular plastics such as PE, PP and the like, and the plastics are added with oxygen at the temperature of about 200 ℃ to accelerate the combustion of the plastics), but in the current vacuum degreasing sintering furnace technology, the oxygen is used in a limited way, because the oxygen reacts with graphite at the temperature of more than 300 ℃, the graphite part is lost. In addition, as with the hydrogen limitation, even if the temperature of the bin is controlled to be about 200 ℃, oxygen is charged into the furnace and passes through different temperature areas before entering the bin, and the graphite piece and the heat insulation cylinder in the reaction area react, particularly the heating material has higher temperature than the temperature of the bin and larger loss.
Disclosure of Invention
The invention aims to provide a vacuum degreasing sintering furnace and a using method thereof, which are used for solving the problems in the prior art and improving degreasing sintering efficiency and product quality.
In order to achieve the purpose, the invention provides the following scheme:
the invention provides a vacuum degreasing sintering furnace, which comprises a furnace body and a carbon fiber heat insulation cylinder arranged in the furnace body, wherein a graphite bin is arranged in the carbon fiber heat insulation cylinder;
the graphite bin is provided with an inner air filling port and an inner air exhaust port, the inner air filling port is communicated with an inner air filling pipe, the inner air exhaust port is communicated with an inner air exhaust pipe, and the inner air filling pipe and the inner air exhaust pipe penetrate through the carbon fiber heat insulation cylinder and the furnace body and extend out of the furnace;
the furnace body is provided with an outer inflation inlet and an outer air exhaust port, the outer inflation inlet is communicated with an outer inflation pipe, the outer air exhaust port is communicated with an outer air exhaust pipe, and the outer air exhaust pipe penetrates through the carbon fiber heat insulation cylinder and extends to a position between the carbon fiber heat insulation cylinder and the graphite material box.
Preferably, an air guide device and a plurality of layers of material plates are arranged in the graphite feed box, the air guide device is positioned between the internal air filling port and the material plates, and air guide holes respectively leading to each layer of material plates are formed in the air guide device.
Preferably, the inner air filling ports are arranged at two ends of the graphite bin, and the inner air exhaust port is arranged in the middle of the graphite bin; or the inner air filling port is arranged in the middle of the graphite feed box, and the inner air pumping port is arranged at two ends of the graphite feed box; or the inner air filling port is arranged at one end of the graphite bin, and the inner air exhaust port is arranged at the other end of the graphite bin.
Preferably, the inner exhaust pipe is sequentially communicated with a first pressure sensor, a first flow regulating valve and a vacuum pump, the first pressure sensor is used for detecting the internal pressure of the graphite bin, the outer exhaust pipe is sequentially communicated with a second flow regulating valve and the vacuum pump, and a second pressure sensor used for detecting the external pressure of the graphite bin is arranged on the furnace body.
Preferably, the inner air exhaust pipe between the inner air exhaust port and the first pressure sensor is further communicated with a third flow regulating valve and a third pressure sensor.
Preferably, a plurality of graphite heating rods are uniformly distributed between the carbon fiber heat insulation barrel and the graphite feed box, a plurality of thermocouples are arranged on the graphite feed box and are used for detecting the temperature of the corresponding area of the graphite feed box.
Preferably, the interior extraction opening sets up the downside of graphite workbin, the bottom flitch downside be equipped with the partial pressure valve on the graphite workbin, the centre or the both ends of graphite workbin upside are equipped with the workbin upper cover.
Preferably, a mass flow meter is respectively arranged on the inner inflation tube and the outer inflation tube.
The invention also provides a use method of the vacuum degreasing sintering furnace in any one of the technical schemes,
when the degreasing process is carried out, the temperature in the graphite bin is controlled, an outer inflation tube is used for filling an outer inflation body into a furnace outside the graphite bin, an inner inflation tube is used for filling inner degreasing process gas into the graphite bin, and the flow of the inner inflation port, the inner exhaust port and the outer inflation port and the outer exhaust port are adjusted to enable the external pressure of the graphite bin to be larger than the internal pressure, so that the binder vapor in the graphite bin cannot diffuse to the outside of the graphite bin;
when the sintering process is carried out, the temperature inside the graphite feed box is controlled, an outer inflation tube is used for filling an outer inflation body into a furnace outside the graphite feed box, an inner inflation tube is used for filling inner sintering process gas into the graphite feed box, the external pressure of the graphite feed box is equal to, slightly larger than or slightly smaller than the internal pressure by adjusting the gas flow of the inner inflation port, the inner exhaust port, the outer inflation port and the outer exhaust port, the polluted gas outside the graphite feed box cannot diffuse into the graphite feed box, the purity of the atmosphere inside the graphite feed box is ensured, and the inner sintering process gas inside the graphite feed box cannot diffuse out of the graphite feed box.
Preferably, the internal degreasing process gas is water vapor, air, hydrogen, inert gas, carbon dioxide, carbon monoxide, methane, propane, acetylene, oxygen or ammonia gas, or a mixed gas of at least two of the above gases; the internal filling sintering process gas is hydrogen, inert gas, carbon dioxide, carbon monoxide, methane, propane, acetylene, oxygen or ammonia gas, or the mixed gas of at least two gases; the outer inflation gas is inert gas or hydrogen or mixed gas of hydrogen and inert gas; when the outer exhaust tube is closed, the outer inflation body can be pumped out through the inner exhaust tube through the partial pressure valve without passing through the product.
Compared with the prior art, the invention has the following technical effects:
the vacuum degreasing sintering furnace mainly fills the process gas into the graphite feed box, and fills the inert gas outside the graphite feed box as an auxiliary gas, so that the atmosphere inside and outside the graphite feed box is isolated, a relatively independent and pure space is formed in the graphite feed box, the influence of various impure atmospheres and pollutants outside the graphite feed box on the sintering of products caused by the entering of the graphite feed box is reduced, and the product quality is improved.
The pressure difference is set to prevent the leakage of adhesive steam during degreasing from polluting the furnace, and the impure atmosphere outside the graphite feed box is pumped out from the outer air pumping port, so that the pollution degree in the furnace is reduced, and the service life of the vacuum degreasing sintering furnace is prolonged.
According to the invention, through different settings of the internal atmosphere and the external atmosphere of the graphite bin, the use of hydrogen during high-temperature sintering and the use of oxygen during low-temperature degreasing become possible, and the technical problems which are urgently desired to be solved by technical personnel in the field are solved, so that the degreasing and sintering time is shortened, the production speed is increased, and the performance and the quality of products are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a system diagram of a conventional vacuum degreasing sintering furnace;
FIG. 2 is a front sectional view of a conventional vacuum degreasing sintering furnace;
FIG. 3 is a reaction effect diagram of introducing hydrogen into a graphite rod at a gradually changing temperature;
FIG. 4 is a system diagram of a vacuum degreasing sintering furnace according to the present invention;
FIG. 5 is a front sectional view of the first embodiment;
FIG. 6 is a front sectional view of the second embodiment;
FIG. 7 is a front sectional view of a third embodiment;
FIG. 8 is a front sectional view of a fourth embodiment;
FIG. 9 is an atmosphere effect diagram of the vacuum degreasing sintering furnace of the invention;
wherein: 1-furnace body, 2-carbon fiber heat insulation cylinder, 3-graphite bin, 4-inner air charging port, 5-inner air pumping port, 6-inner air charging pipe, 7-inner air pumping pipe, 8-outer air charging port, 9-outer air pumping port, 10-outer air charging pipe, 11-outer air pumping pipe, 12-air guide device, 13-material plate, 14-first pressure sensor, 15-first flow regulating valve, 16-vacuum pump, 17-second flow regulating valve, 18-second pressure sensor, 19-third flow regulating valve, 20-third pressure sensor, 21-graphite heating rod, 22-thermocouple, 23-pressure dividing valve, 24-bin upper cover and 25-mass flowmeter.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.
The invention aims to provide a vacuum degreasing sintering furnace and a using method thereof, which are used for solving the problems in the prior art and improving degreasing sintering efficiency and product quality.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Example one
As shown in fig. 4-5: the embodiment provides a vacuum degreasing sintering furnace, including furnace body 1 with set up in the thermal-insulated section of thick bamboo 2 of the inside carbon fiber of furnace body 1, the inside graphite workbin 3 that is equipped with of the thermal-insulated section of thick bamboo 2 of carbon fiber, the centre of the 3 upside of graphite workbin is equipped with workbin upper cover 24. A plurality of graphite heating rods 21 are uniformly distributed between the carbon fiber heat insulation barrel 2 and the graphite feed box 3 along the circumferential direction, a plurality of thermocouples 22 are respectively arranged on the upper side and the lower side of the graphite feed box 3, and the thermocouples 22 are respectively used for detecting the temperature of the upper side and the lower side of the graphite feed box 3.
An inner gas filling port 4 and an inner gas extraction port 5 are arranged on the graphite feed box 3, the inner gas filling port 4 is communicated with an inner gas filling pipe 6, the inner gas filling pipe 6 is used for introducing process gas into the graphite feed box 3, the inner gas extraction port 5 is communicated with an inner gas extraction pipe 7, and the inner gas filling pipe 6 and the inner gas extraction pipe 7 both penetrate through the carbon fiber heat insulation cylinder 2 and the furnace body 1 and extend out of the furnace; an outer inflation inlet 8 and an outer gas extraction opening 9 are arranged on the furnace body 1, the outer inflation inlet 8 is communicated with an outer inflation tube 10, the outer inflation tube 10 is used for injecting inert gas between the furnace body 1 and the carbon fiber heat insulation barrel 2, the outer gas extraction opening 9 is communicated with an outer gas extraction tube 11, and the outer gas extraction tube 11 penetrates through the carbon fiber heat insulation barrel 2 and extends to a position between the carbon fiber heat insulation barrel 2 and the graphite material box 3. In the embodiment, the inner air charging ports 4 are arranged at two ends of the upper side of the graphite feed box 3, and the inner air exhaust port 5 is arranged in the middle of the lower side of the graphite feed box 3; the outer inflation inlet 8 is arranged on the upper side of the furnace body 1, the outer air exhaust inlet 9 is arranged on the lower side of the furnace body 1, the process gas enters the graphite bin 3 through the inner inflation pipe 6, the air flow flows through the product and is exhausted through the inner exhaust pipe 7, meanwhile, the inert gas enters the furnace through the outer inflation pipe 10 and is exhausted through the outer exhaust pipe 11, and the effect that the atmosphere inside and outside the graphite bin 3 is different as shown in fig. 9 is formed.
Further, an air guide device 12 and a plurality of layers of material plates 13 are arranged in the graphite feed box 3, the material plates 13 are arranged in a multi-layer double-row mode, ceramic plates for placing product blanks are arranged on the material plates 13, the air guide device 12 is located between the inner air filling port 4 and the material plates 13, two air guide devices 12 are respectively arranged on two outer sides of each double-row material plate 13, the air guide devices 12 can be plate-shaped or tubular, and air guide holes respectively leading to each layer of material plates 13 are formed in the air guide devices 12, so that process gas can uniformly enter each layer.
As shown in fig. 4, the inner inflation tube 6 and the outer inflation tube 10 are respectively provided with a mass flow meter 25; the first pressure sensor 14, the first flow regulating valve 15 and the vacuum pump 16 form a degreasing pipeline system and are communicated with the inner exhaust pipe 7, when a degreasing process is carried out, the first flow regulating valve 15 is opened, and the first pressure sensor 14 is used for detecting the internal pressure of the graphite feed box 3; the outer exhaust pipe 11 is sequentially communicated with a second flow regulating valve 17 and a vacuum pump 16, and the furnace body 1 is provided with a second pressure sensor 18 for detecting the external pressure of the graphite bin 3. By adjusting the flow rates of the two mass flowmeters 25, the first flow regulating valve 15 and the second flow regulating valve 17, the internal pressure and the external pressure of the graphite bin 3 can be adjusted, and the real-time monitoring can be carried out through the first pressure sensor 14 and the second pressure sensor 18 respectively. The inner extraction pipe 7 is also communicated with a third flow regulating valve 19 and a third pressure sensor 20 for carrying out partial pressure sintering process.
The embodiment also provides a using method of the vacuum degreasing sintering furnace, when a degreasing process is performed, the temperature inside the graphite bin 3 is controlled, an inert gas such as nitrogen or argon is filled into the furnace outside the graphite bin 3 through the outer gas filling pipe 10, degreasing process gas is filled into the graphite bin 3 through the inner gas filling pipe 6, the degreasing process gas is generally selected from the inert gas, an oxygen-containing medium such as water vapor or air can be selected, hydrogen can be selected to increase the degreasing rate, when the oxygen-containing medium gas is selected, the temperature of the graphite bin 3 is controlled to be not higher than 300 ℃, preferably about 200 ℃ so as to avoid the sensitive temperature of reaction between oxygen and graphite, and the external pressure of the graphite bin 3 is larger than the internal pressure through adjusting the gas flow rates of the inner gas filling port 4, the inner gas pumping port 5, the outer gas filling port 8 and the outer gas pumping port 9, so that binder vapor inside the graphite bin 3 does not diffuse to the outside of the graphite bin 3 to pollute the furnace, such as the, A carbon fiber heat insulation cylinder 2 and a graphite piece.
When the sintering process is carried out, the temperature inside the graphite bin 3 is controlled, inert gas such as nitrogen or argon is filled into the furnace outside the graphite bin 3 by using the outer gas filling pipe 10, sintering process gas is filled into the graphite bin 3 by using the inner gas filling pipe 6, the sintering process gas is generally selected from inert gas and can also be selected from hydrogen, when hydrogen is selected, the temperature of the graphite bin 3 is controlled to be not lower than 1200 ℃, preferably 1300 ℃, the external pressure of the graphite bin 3 is equal to, slightly larger than or slightly smaller than the internal pressure by adjusting the gas flow of the inner gas filling port 4 and the inner gas extraction port 5 as well as the gas flow of the outer gas filling port 8 and the outer gas extraction port 9, the larger and smaller pressure means that the internal and external pressure difference of the graphite bin 3 is smaller than the maximum pressure which the graphite bin 3 can bear under the premise of ensuring the sealing, and because the graphite bin 3 has certain sealing property, the pollution gas outside the graphite bin 3 can, the atmosphere in the graphite feed box 3 is ensured to be pure, and sintering process gas in the graphite feed box 3 cannot diffuse to the outside of the graphite feed box 3 to consume furnace parts such as the carbon fiber heat insulation cylinder 2 and graphite pieces.
Example two
As shown in fig. 6: the difference between this embodiment and the first embodiment is: the inner air filling port 4 is arranged in the middle of the upper side of the graphite feed box 3, the inner air pumping port 5 is arranged at two ends of the lower side of the graphite feed box 3, two adjacent ends of the two rows of material plates 13 are respectively provided with an air guide device 12, the feed box upper cover 24 is arranged at two ends of the upper side of the graphite feed box 3, and the outer air pumping port 9 is arranged at the lower side of the furnace body 1. The rest technical characteristics and the using method are shown in the first embodiment.
EXAMPLE III
As shown in fig. 7: the difference between this embodiment and the first embodiment is: interior gas filling port 4 sets up the one end in 3 upsides of graphite workbin, like the right-hand member, and interior extraction opening 5 sets up the other end in 3 downside of graphite workbin, like the left end, flitch 13 is the multilayer setting, only is equipped with air guide device 12 at flitch 13 right-hand member, and outer gas filling port 9 sets up the downside at furnace body 1. The rest technical characteristics and the using method are shown in the first embodiment.
Example four
As shown in fig. 8: the difference between this embodiment and the first embodiment is: when the outer air exhaust pipe 11 is closed, the pressure dividing valve 23 can be arranged on the graphite feed box 3 on the lower side of the material plate 13 at the bottommost layer, the pressure dividing valve 23 is close to the inner air exhaust opening 5, and due to the obstruction of the material plate 13 on the upper side, the polluted gas entering the graphite feed box 3 through the pressure dividing valve 23 can be directly exhausted through the inner air exhaust opening 5 without polluting the blank of the product, so that the basically same technical effect is realized.
The principle and the implementation mode of the present invention are explained by applying specific examples in the present specification, and the above descriptions of the examples are only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (8)
1. A vacuum degreasing sintering furnace is characterized in that: the furnace comprises a furnace body and a carbon fiber heat insulation cylinder arranged in the furnace body, wherein a graphite bin is arranged in the carbon fiber heat insulation cylinder;
the graphite bin is provided with an inner air filling port and an inner air exhaust port, the inner air filling port is communicated with an inner air filling pipe, the inner air exhaust port is communicated with an inner air exhaust pipe, and the inner air filling pipe and the inner air exhaust pipe penetrate through the carbon fiber heat insulation cylinder and the furnace body and extend out of the furnace;
an outer inflation inlet and an outer gas extraction opening are arranged on the furnace body, the outer inflation inlet is communicated with an outer inflation pipe, the outer inflation pipe is used for injecting inert gas between the furnace body and the carbon fiber heat insulation cylinder, the outer gas extraction opening is communicated with an outer gas extraction pipe, and the outer gas extraction pipe penetrates through the carbon fiber heat insulation cylinder and extends to a position between the carbon fiber heat insulation cylinder and the graphite bin;
the inner exhaust pipe is sequentially communicated with a first pressure sensor, a first flow regulating valve and a vacuum pump, the first pressure sensor is used for detecting the internal pressure of the graphite bin, the outer exhaust pipe is sequentially communicated with a second flow regulating valve and the vacuum pump, and a second pressure sensor used for detecting the external pressure of the graphite bin is arranged on the furnace body;
and the inner inflation tube and the outer inflation tube are respectively provided with a mass flow meter.
2. The vacuum degreasing sintering furnace according to claim 1, wherein: the graphite material box is internally provided with a gas guide device and a plurality of layers of material plates, the gas guide device is positioned between the internal gas filling port and the material plates, and the gas guide device is provided with gas guide holes respectively leading to each layer of material plates.
3. The vacuum degreasing sintering furnace according to claim 1 or 2, wherein: the inner air filling ports are arranged at two ends of the graphite bin, and the inner air pumping port is arranged in the middle of the graphite bin; or the inner air filling port is arranged in the middle of the graphite feed box, and the inner air pumping port is arranged at two ends of the graphite feed box; or the inner air filling port is arranged at one end of the graphite bin, and the inner air exhaust port is arranged at the other end of the graphite bin.
4. The vacuum degreasing sintering furnace according to claim 1, wherein: the inner air exhaust pipe between the inner air exhaust port and the first pressure sensor is also communicated with a third flow regulating valve and a third pressure sensor.
5. The vacuum degreasing sintering furnace according to claim 1, wherein: a plurality of graphite heating rods are uniformly distributed between the carbon fiber heat insulation cylinder and the graphite feed box, a plurality of thermocouples are arranged on the graphite feed box and are used for detecting the temperature of the corresponding area of the graphite feed box.
6. The vacuum degreasing sintering furnace according to claim 2, wherein: interior extraction opening sets up the downside of graphite workbin, the bottom flitch downside be equipped with the partial pressure valve on the graphite workbin, the centre or the both ends of graphite workbin upside are equipped with the workbin upper cover.
7. The method of using the vacuum degreasing sintering furnace as set forth in any one of claims 1 to 6, wherein: when the degreasing process is carried out, the temperature in the graphite bin is controlled, an outer inflation tube is used for filling an outer inflation body into a furnace outside the graphite bin, an inner inflation tube is used for filling inner degreasing process gas into the graphite bin, and the flow of the inner inflation port, the inner exhaust port and the outer inflation port and the outer exhaust port are adjusted to enable the external pressure of the graphite bin to be larger than the internal pressure, so that the binder vapor in the graphite bin cannot diffuse to the outside of the graphite bin;
when the sintering process is carried out, the temperature inside the graphite feed box is controlled, an outer inflation tube is used for filling an outer inflation body into a furnace outside the graphite feed box, an inner inflation tube is used for filling inner sintering process gas into the graphite feed box, the external pressure of the graphite feed box is equal to, slightly larger than or slightly smaller than the internal pressure by adjusting the gas flow of the inner inflation port, the inner exhaust port, the outer inflation port and the outer exhaust port, the polluted gas outside the graphite feed box cannot diffuse into the graphite feed box, the purity of the atmosphere inside the graphite feed box is ensured, and the inner sintering process gas inside the graphite feed box cannot diffuse out of the graphite feed box.
8. The vacuum degreasing sintering furnace according to claim 7, wherein: the internal degreasing process gas is water vapor, air, hydrogen, inert gas, carbon dioxide, carbon monoxide, methane, propane, acetylene, oxygen or ammonia gas, or a mixed gas of at least two gases; the internal filling sintering process gas is hydrogen, inert gas, carbon dioxide, carbon monoxide, methane, propane, acetylene, oxygen or ammonia gas, or the mixed gas of at least two gases; the outer inflation gas is inert gas or hydrogen or mixed gas of hydrogen and inert gas; when the outer exhaust tube is closed, the outer inflation body can be pumped out through the inner exhaust tube through the partial pressure valve without passing through the product.
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| Application Number | Priority Date | Filing Date | Title |
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| PCT/CN2018/122642 WO2020124544A1 (en) | 2018-12-21 | 2018-12-21 | Vacuum degreasing and sintering furnace and usage method therefor |
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| CN110603417A CN110603417A (en) | 2019-12-20 |
| CN110603417B true CN110603417B (en) | 2021-06-18 |
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| CN111451498B (en) * | 2020-02-28 | 2022-04-26 | 福建省长汀金龙稀土有限公司 | Degreasing method for powder metallurgy sintering |
| CN111283189A (en) * | 2020-03-26 | 2020-06-16 | 宁波恒普真空技术有限公司 | Vacuum degreasing sintering furnace with double internal pumping down pipelines |
| WO2021217474A1 (en) * | 2020-04-29 | 2021-11-04 | 宁波恒普真空技术有限公司 | Bidirectional atmosphere control process and bidirectional atmosphere sintering furnace |
| CN111468730A (en) * | 2020-05-15 | 2020-07-31 | 中山市浩雅生物科技有限公司 | Preparation method of orthopedic implant |
| CN112595128B (en) * | 2020-12-29 | 2023-03-03 | 湖南维尚科技有限公司 | Process gas introduction method of high-temperature sintering furnace |
| CN113523284B (en) * | 2021-05-25 | 2023-04-07 | 宁波市鑫瑞鸿新材料科技有限公司 | Rapid thermal desorption sintering integrated forming metal feed and application method thereof |
| CN115410814B (en) * | 2022-08-04 | 2023-12-15 | 南通三优佳磁业有限公司 | Sintering device for manganese zinc ferrite magnetic powder |
| CN115090878B (en) * | 2022-08-11 | 2023-07-04 | 山东金珠材料科技有限公司 | Integrally formed aging steel structure, preparation method and preparation device |
| CN115523753A (en) * | 2022-09-17 | 2022-12-27 | 江苏晨朗电子集团有限公司 | Preparation facilities of abundant tombarthite permanent magnet material |
| CN115446311B (en) * | 2022-09-19 | 2023-07-25 | 株洲坤锐硬质合金有限公司 | Vacuum degreasing sintering furnace for hard alloy production |
| CN117399622A (en) * | 2023-12-14 | 2024-01-16 | 西安隆源热技术有限公司 | Rapid sintering densification device and method for metal parts |
| CN117464006B (en) * | 2023-12-28 | 2024-03-12 | 湘潭大学 | Multi-zone control vacuum sintering furnace and temperature field and atmosphere field control method thereof |
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| JP2000017305A (en) * | 1998-06-30 | 2000-01-18 | Shimazu Mekutemu Kk | Degreasing sintering furnace |
| CN2489287Y (en) * | 2001-03-21 | 2002-05-01 | 赵宇靖 | Rare earth permanent-magnetic vacuum retort furnace |
| JP2003302166A (en) * | 2002-04-11 | 2003-10-24 | Denso Corp | Microwave baking furnace and method of microwave baking |
| CN2718480Y (en) * | 2004-03-26 | 2005-08-17 | 戴煜 | Partial pressure controlling vacuum degreasing sintering furnace |
| US20080160472A1 (en) * | 2006-12-27 | 2008-07-03 | Yu-Feng Chang | Sinter furnace for sapphire crystal growth |
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| JP7144617B2 (en) | 2022-09-29 |
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