CN109530685B - Vacuum degreasing sintering forming method - Google Patents
Vacuum degreasing sintering forming method Download PDFInfo
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- CN109530685B CN109530685B CN201811641712.6A CN201811641712A CN109530685B CN 109530685 B CN109530685 B CN 109530685B CN 201811641712 A CN201811641712 A CN 201811641712A CN 109530685 B CN109530685 B CN 109530685B
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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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Abstract
The invention provides a vacuum sintering forming method, which comprises the steps of feeding; vacuumizing: degreasing: introducing a current-carrying gas into the vacuum degreasing sintering furnace, heating and vacuumizing according to a preset degreasing heating curve, detecting the air pressure of the overflowing area and the air pressure of the wax catching tank group, keeping the difference value of the air pressure of the overflowing area and the air pressure of the wax catching tank group within a set pressure difference range by adjusting the flow rate of the current-carrying gas and the vacuum degree of the wax catching tank group, and allowing the steam wax generated in an effective heating area to enter the wax catching tank group along with the current-carrying gas; sintering at high temperature and cooling. In this technical scheme, come control current-carrying gas flow and catch the vacuum of wax jar group according to the atmospheric pressure of the scattered district of excessive and effective zone of heating to make the vapour wax in the effective zone of heating can directly get into in catching the wax jar through the inner wall of boiler barrel, compare prior art, vapour wax collection effect is better, and can effectively reduce the pollution to the furnace body, reduces the influence to next blank sintering quality.
Description
Technical Field
The invention relates to the technical field of industrial furnaces, in particular to a vacuum degreasing sintering forming method.
Background
The conventional dewaxing process is to arrange a vertical or horizontal wax catching tank outside a furnace body, wherein the horizontal wax catching tank is directly connected with the lower part of a furnace wall and is connected with the vertical wax catching tank, and one side of the vertical wax catching tank is connected with a vacuum pump set. In the sintering process, the vacuum pump continuously vacuumizes the furnace body; the temperature in the furnace body rises, the binder and the forming agent are gradually gasified, pumped out by a vacuum pump set and condensed in a wax catching tank through a cooling system.
Although most of the adhesive or the forming agent can be contained in the wax catching tank by the traditional dewaxing equipment, the adhesive or the forming agent exists in a high-temperature furnace body in a gas form, but a cooling waterproof layer is arranged on the inner side of the furnace wall, so that part of the adhesive or the forming agent is solidified on the furnace wall when the adhesive or the forming agent is not drawn into the wax catching tank, the furnace body is polluted, and the quality of next product sintering is possibly influenced.
Disclosure of Invention
The invention mainly aims to provide a vacuum degreasing sintering forming method, and aims to solve the problems of furnace body pollution and low sintering quality caused by incomplete removal of vapor wax generated in a dewaxing stage in a sintering process.
In order to achieve the above object, a vacuum degreasing sintering system for implementing the vacuum degreasing sintering method includes a vacuum degreasing sintering furnace and a wax catching tank group, wherein the vacuum degreasing sintering furnace includes a furnace cylinder, an effective heating zone surrounded by a heat insulating layer and disposed in the furnace cylinder, an overflow zone formed by the heat insulating layer and an inner wall of the furnace cylinder, and a wax catching pipeline penetrating the heat insulating layer and the furnace cylinder, one end of the wax catching pipeline is communicated with the effective heating zone, and the other end of the wax catching pipeline is communicated with the wax catching tank group, and the vacuum degreasing sintering method includes:
1) feeding: placing a blank to be sintered into an effective heating area of the vacuum degreasing sintering furnace:
2) vacuumizing: vacuumizing the vacuum degreasing sintering furnace and the wax catching tank group until a set pressure value is reached;
3) degreasing: introducing a current-carrying gas into the vacuum degreasing sintering furnace, heating and vacuumizing according to a preset degreasing heating curve, detecting the air pressure of the overflow area and the air pressure of the wax catching tank group, adjusting the flow rate of the current-carrying gas and adjusting the vacuum degree of the wax catching tank group according to the difference value between the air pressure of the overflow area and the air pressure of the wax catching tank group so as to keep the difference value between the air pressure of the overflow area and the air pressure of the wax catching tank group within a set pressure difference range, and allowing vapor wax generated in the effective heating area to enter the wax catching tank group along with the current-carrying gas through the wax catching pipeline;
4) sintering at high temperature;
5) and (6) cooling.
Preferably, in the degreasing stage, the air pressure of the overflow area is greater than the air pressure of the wax catching tank group, and the set pressure difference range is 10 kpa to 30 kpa.
Preferably, the vacuum degreasing sintering system comprises a vacuum pump set, one end of the vacuum pump set is communicated with the wax catching tank set and vacuumizes the furnace cylinder body through the wax catching tank set, the other end of the vacuum pump set is connected with the furnace cylinder body and feeds gas into the furnace cylinder body, and the vacuum degree of the wax catching tank set is adjusted by adjusting the size of a valve of the vacuum pump set.
Preferably, the degreasing temperature-rising curve is as follows: heating the mixture from room temperature to 500-600 ℃ at a heating rate of 1-5 ℃/min, and preserving the heat for 1-2 hours.
Preferably, in the vacuum-pumping stage, the set pressure value is 5-20 Pa.
Preferably, in the high-temperature sintering stage, after the degreasing stage is finished, the temperature is raised to 1100-1500 ℃ at a temperature rise rate of 5-20 ℃/min, and the temperature is maintained for 1-2 hours.
Preferably, the high-temperature sintering stage further includes stopping introducing carrier gas after the degreasing stage is finished, vacuumizing to a target pressure value, and introducing protective gas with a preset flow rate.
Preferably, the carrier gas is one of an inert gas, hydrogen or nitrogen.
In the degreasing stage of the vacuum degreasing sintering forming method, the temperature is raised and the vacuum pumping is carried out according to a preset degreasing temperature rise curve, the air pressure of an overflow area and the air pressure of a wax catching tank group are detected, when the difference value of the air pressure of the overflow area and the air pressure of the wax catching tank group reaches a set value, current-carrying gas is introduced into a vacuum degreasing sintering furnace, and steam wax generated in an effective heating area enters the wax catching tank group along with the current-carrying gas through a wax catching pipeline. In this technical scheme, in the degrease stage, the gas in the effective heating district includes carrier gas and vapour wax, because the production of vapour wax makes the effective heating district promptly catch the continuous change of pressure in the wax jar group, the difference of atmospheric pressure through control overflow scattered district and effective heating district is in certain extent, can make the vapour wax in the effective heating district can directly get into in catching the wax jar not passing through the inner wall of furnace barrel, compare prior art, vapour wax collection effect is better, and further reduced the vapour wax and solidified probability on the inner wall of furnace barrel, can effectively reduce the pollution to the furnace body, reduce the influence to next blank sintering quality.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a flow chart of a vacuum degreasing sintering molding method according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a vacuum degreasing sintering system according to an embodiment of the present invention;
FIG. 3 is a sectional view of a vacuum degreasing sintering furnace according to an embodiment of the present invention.
The reference numbers illustrate:
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
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 derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "connected," "secured," and the like are to be construed broadly, and for example, "secured" may be a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In addition, the technical solutions in the embodiments of the present invention may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination of technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
Referring to fig. 1, 2 and 3, the vacuum degreasing sintering system for implementing the vacuum degreasing sintering molding method of the present invention includes a vacuum degreasing sintering furnace 100 and a wax catching tank set 200, where the vacuum degreasing sintering furnace 100 includes a furnace cylinder 110, an effective heating area 112 surrounded by a heat insulating layer 111 and disposed in the furnace cylinder, an overflow area 113 formed by the heat insulating layer 111 and an inner wall of the furnace cylinder 110, and a wax catching pipeline 114 penetrating the heat insulating layer 111 and the furnace cylinder 110, one end of the wax catching pipeline 114 is communicated with the effective heating area 112, and the other end of the wax catching pipeline 114 is communicated with the wax catching tank set 200, and referring to fig. 1, the vacuum degreasing sintering molding method includes:
1) feeding: placing the blank to be sintered into the effective heating zone 112 of the vacuum degreasing sintering furnace 100:
it should be noted that the material of the thermal insulation layer 111 is preferably carbon felt or other high-temperature thermal insulation materials such as polycrystalline mullite fiber and corundum. The heat insulation layer 111 is arranged in the furnace barrel body 110, the space in the furnace barrel can be divided into an effective heating area 112 and an overflow area 113, and a heating body and a bracket for bearing a blank to be sintered are arranged in the effective heating area 112. The furnace cylinder 110 is provided with a gas inlet channel, and the gas entering through the gas inlet channel overflows through an overflow area 113 to reach an effective heating area 112. The heat insulation layer 111 can insulate heat in the effective heating area 112, and the overflow area 113 can homogenize the gas entering the effective heating area 112. It will be appreciated that the insulating layer 111 has a certain porosity that allows for the ingress and egress of gases, while allowing for a certain pressure differential between the effusion region 113 and the active heating region 112 due to the presence of the insulating layer 111.
2) Vacuumizing: vacuumizing the vacuum degreasing sintering furnace 100 and the wax catching tank group 200 until a set pressure value is reached;
the vacuum degreasing sintering system further comprises a vacuum pump unit 300, wherein one end of the vacuum pump unit 300 is communicated with the wax catching tank unit 200, and the furnace cylinder body 110 is vacuumized by the wax catching tank unit 200 until a set pressure value is reached, preferably, the set pressure value is 5-20 pa, such as 8 pa, 10 pa, 15 pa, 18 pa, and the like.
It should be noted that the wax catching tank set 200 includes a horizontal wax catching tank 201 and a vertical wax catching tank 202 which are connected in sequence, the horizontal wax catching tank 201 is arranged close to the vacuum degreasing sintering furnace 100 and is located below the vacuum degreasing sintering furnace 100, the pressure difference control device 400 detects the air pressure in the horizontal wax catching tank 201, and the vertical wax catching tank 202 is connected with the vacuum pump set 300. During vacuumizing, the air inlet channel of the vacuum degreasing sintering furnace 100 is closed, the vacuum pump unit 300 is started, and the vacuum pump unit 300 performs vacuumizing treatment on the vertical wax catching tank 202, the horizontal wax catching tank 201 and the vacuum degreasing sintering furnace 100. It will be appreciated that, during evacuation, the air in the effective heating area 112 is evacuated before the air in the effusion area 113, i.e., the effective heating area 112 reaches a negative pressure before the effusion area 113.
3) Degreasing: introducing carrier gas into the vacuum degreasing sintering furnace 100, heating and vacuumizing according to a preset degreasing heating curve, detecting the air pressure of the overflowing area 113 and the air pressure of the wax catching tank group 200, adjusting the flow rate of the carrier gas and the vacuum degree of the wax catching tank group 200 according to the difference value between the air pressure of the overflowing area 113 and the air pressure of the wax catching tank group 200, so that the difference value between the air pressure of the overflowing area 113 and the air pressure of the wax catching tank group 200 is kept in a set pressure difference range, and steam wax generated in the effective heating area 112 enters the wax catching tank group 200 along with the carrier gas through the wax catching pipeline 114;
the vacuum degreasing sintering system further comprises a pressure difference control device 400, wherein the pressure difference control device 400 is connected with the furnace cylinder body 110 and detects the air pressure of the overflow area 113, and the pressure difference control device 400 is further connected with the wax catching tank group 200 and detects the air pressure of the wax catching tank group 200. One end of the vacuum pump unit 300 is communicated with the wax catching tank unit 200, the other end of the vacuum pump unit 300 is connected with the furnace cylinder body 110, and after gas is introduced into the furnace cylinder body 110 for vacuumizing, the temperature is raised and the degreasing is carried out at the same time. Firstly, introducing carrier gas into the vacuum degreasing sintering furnace 100, heating according to a preset degreasing heating curve, and simultaneously vacuumizing. As the temperature in the effective heating zone 112 increases, the forming agent or binder, etc. in the blank to be sintered overflows from the blank to be sintered to form vapor wax. The generation of the vapor wax raises the air pressure in the effective heating area 112, and when the air pressure in the effective heating area 112 is higher than the air pressure in the overflow area 113, the vapor wax flows back to the overflow area 113, so that the vapor wax is solidified on the furnace cylinder 111 to pollute the furnace body. Therefore, it is necessary to maintain the pressure in the effusion region 113 to be greater than the pressure in the active heating region 112. Specifically, the air pressure of the overflow area 113 and the air pressure of the wax catching tank group 200 are detected, and the flow rate of the carrier gas and/or the vacuum degree of the wax catching tank group 200 are/is adjusted according to the difference between the air pressure of the overflow area 113 and the air pressure of the wax catching tank group 200, so that the difference between the air pressure of the overflow area 113 and the air pressure of the wax catching tank group 200 is kept within a set pressure difference range. The vacuum degree of the wax catching tank set 200 can be adjusted by adjusting the valve size of the vacuum pump set 300.
When the air pressure of the overflow area 113 is too high, it is stated that the air pressure of the overflow area 113 is far higher than the air pressure of the effective heating area 112, at this time, the diffusion speed of the carrier gas in the overflow area 113 is fast, and after the carrier gas enters the effective heating area 112 through the heat insulation layer 111, the vapor wax is driven to rapidly enter the wax catching tank set 200 through the wax catching pipeline 114, at this time, the utilization rate of the carrier gas is reduced due to the fact that the flow speed of the carrier gas is too high, waste of the carrier gas is caused, and accordingly, the flow rate of the carrier gas needs to be reduced and the vacuum degree of the wax catching tank set 200 needs to. When the gas pressure in the overflow area 113 is too low, that is, the gas pressure in the effective heating area 112 is too high, at this time, the carrier gas may not diffuse into the effective heating area 112 or the diffusion speed may be too slow, or even the vapor wax may diffuse into the overflow area 113, so that dewaxing is insufficient, and accordingly, the flow rate of the carrier gas needs to be increased and the vacuum degree of the wax trap tank set 200 needs to be increased. Therefore, the difference between the air pressure of the spill area 113 and the air pressure of the wax trap tank set 200 should be within a reasonable range. In the present embodiment, the differential pressure is set to be in the range of 10 kpa to 30 kpa.
Preferably, the vacuum pump unit 300 is a roots vacuum pump unit 300, and the differential pressure control device 400 includes a first pressure detection device for detecting the air pressure of the overflow area 113 and a second pressure detection device for detecting the air pressure of the wax catching tank unit 200. Further, the first pressure detecting means is an electro contact vacuum pressure gauge, and the second pressure detecting means is a differential pressure transmitter. In addition, the differential pressure control device 400 further comprises a controller, wherein the controller is connected with the first pressure detection device and the second pressure detection device, obtains the measurement values of the first pressure detection device and the second pressure detection device, judges the difference value of the measurement values, and controls the flow rate of the carrier gas and the vacuum degree of the wax-catching tank group 200 to enable the difference value of the measurement values of the first pressure detection device and the second pressure detection device to meet the set differential pressure range.
Further, the vacuum degreasing sintering system further comprises a transformer 600 and a control cabinet 700, wherein the transformer 600 is used for stabilizing and controlling the voltage of the whole system, and the control cabinet 700 is used for controlling the operation of the whole system, such as power on and power off. The carrier gas is one or more of inert gas, hydrogen or nitrogen.
The vapor wax is a gaseous substance formed by volatilizing an organic substance such as a forming agent and a binder in the material to be sintered at a high temperature. Further, since the effective heating zone 112 communicates with the wax trap tank group 200 through the wax trap passage, the air pressure in the wax trap tank is equivalent to that of the effective heating zone 112.
4) Sintering at high temperature;
in the degreasing phase, the forming agent and the binder in the blank to be sintered have condensed on the condensation bars in the wax trap tank group 200. At the moment, according to a set sintering temperature rise curve, after the degreasing stage is finished, the temperature is kept for 1-2 hours at the temperature rise rate of 1100-1500 ℃ at the speed of 5-20 ℃/min. And after the degreasing stage is finished, stopping introducing the carrier gas, vacuumizing to a certain negative pressure value, and introducing protective gas with preset flow to prevent the blank to be sintered from being oxidized. The shielding gas may be nitrogen.
5) And (6) cooling.
The vacuum degreasing sintering system further comprises a cooling device 500, wherein cooling flow channels are formed in the inner wall of the furnace cylinder body 110 and the inner wall of the wax catching tank group 200, cooling liquid is arranged in the cooling flow channels, and the cooling liquid circularly flows in the inner wall of the furnace cylinder body 110, the inner wall of the wax catching tank and the cooling device 500 under the action of the cooling device 500. And after the high-temperature sintering stage is finished, sintering the blank to be sintered to be compact to form a formed blank. And cooling the formed blank to take out the formed blank. In one embodiment, the shaped blank is cooled by the cooling device 500 after being shaped and cooled by a furnace. In other embodiments, a gas circulation channel and a heat exchanger may be further disposed on the furnace cylinder 110, and the gas in the furnace cylinder 110 is pumped out and re-introduced into the furnace cylinder 110 after passing through the heat exchanger, so as to accelerate the heat dissipation.
In the technical scheme of this embodiment, in the degreasing stage, the gas in the effective heating area 112 includes carrier gas and vapor wax, because the production of vapor wax makes the effective heating area 112 promptly catch the atmospheric pressure in the wax jar group 200 and constantly change, through controlling the difference of the atmospheric pressure of the district 113 of spilling over and effective heating area 112 in certain extent, can make the vapor wax in the effective heating area 112 can not flow backward to the district 113 of spilling over but directly mirror the wax catching pipeline 114 and get into in catching the wax jar group 200, compare prior art, vapor wax collection effect is better, and further reduced the probability that the vapor wax solidifies on the inner wall of furnace barrel, can effectively reduce the pollution to the furnace body, reduce the influence to next blank sintering quality.
The following provides a specific example of the vacuum degreasing sintering molding method in the embodiment of the present invention.
Specific example 1:
1) feeding: placing an aluminum alloy blank to be sintered into an effective heating zone 112 of a vacuum degreasing sintering furnace 100:
2) vacuumizing: vacuumizing the vacuum degreasing sintering furnace 100 and the wax catching tank group 200 until the pressure value is 6 Pa;
3) degreasing: and (3) introducing inert gas into the vacuum degreasing sintering furnace 100, heating the mixture from room temperature to 500 ℃ according to the heating rate of 2 ℃/min, preserving the heat for 1 hour, and vacuumizing the mixture. Detecting the air pressure of the overflow area 113 and the air pressure of the wax catching tank group 200, adjusting the flow rate of the inert gas and the vacuum degree of the wax catching tank group to keep the difference value between the air pressure of the overflow area 113 and the air pressure of the wax catching tank group 200 at 15 kilopascals, and allowing the vapor wax generated in the effective heating area 112 to enter the wax catching tank group 200 through the wax catching pipeline 114 along with the inert gas;
4) sintering at high temperature;
the temperature is continuously increased to 1300 ℃ at the temperature increasing rate of 5 ℃/min, and the temperature is kept for 1 hour.
5) And (6) cooling.
And cooling to room temperature along with the furnace, and taking out the aluminum alloy formed part.
Specific example 2:
1) feeding: placing the alumina blank to be sintered into the effective heating zone 112 of the vacuum degreasing sintering furnace 100:
2) vacuumizing: vacuumizing the vacuum degreasing sintering furnace 100 and the wax catching tank group 200 until the pressure value is 10 Pa;
3) degreasing: and introducing nitrogen gas into the vacuum degreasing sintering furnace 100, heating the furnace from room temperature to 600 ℃ according to the heating rate of 4 ℃/min, preserving the heat for 1.5 hours, and vacuumizing the furnace. Detecting the air pressure of the overflow area 113 and the air pressure of the wax catching tank group 200, adjusting the flow rate of nitrogen and the vacuum degree of the wax catching tank group to keep the difference value between the air pressure of the overflow area 113 and the air pressure of the wax catching tank group 200 at 20 kilopascals, and allowing vapor wax generated in the effective heating area 112 to enter the wax catching tank group 200 through the wax catching pipeline 114 along with the nitrogen;
4) sintering at high temperature;
the temperature is continuously raised to 1450 ℃ at the temperature raising rate of 10 ℃/min, and the temperature is kept for 2 hours.
5) And (6) cooling.
Cooling to room temperature along with the furnace, and taking out the alumina formed part.
Specific example 3:
1) feeding: placing a stainless steel blank to be sintered into the effective heating zone 112 of the vacuum degreasing sintering furnace 100:
2) vacuumizing: vacuumizing the vacuum degreasing sintering furnace 100 and the wax catching tank group 200 until the pressure value is 15 Pa;
3) degreasing: introducing inert gas into the vacuum degreasing sintering furnace 100, heating the furnace from room temperature to 500 ℃ according to the heating rate of 2 ℃/min, preserving the heat for 1 hour, simultaneously vacuumizing, detecting the air pressure of the overflow area 113 and the air pressure of the wax catching tank group 200, adjusting the flow of the inert gas and the vacuum degree of the wax catching tank group to keep the difference value of the air pressure of the overflow area 113 and the air pressure of the wax catching tank group 200 at 25 kilopascals, and allowing the vapor wax generated in the effective heating area 112 to enter the wax catching tank group 200 through the wax catching pipeline 114 along with nitrogen;
4) sintering at high temperature;
the temperature is continuously raised to 1200 ℃ at the temperature raising rate of 15 ℃/min, and the temperature is kept for 1 hour.
5) And (6) cooling.
Cooling to room temperature along with the furnace, and taking out the stainless steel formed part.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (6)
1. A vacuum degreasing sintering forming method is characterized in that a vacuum degreasing sintering system for implementing the vacuum degreasing sintering forming method comprises a vacuum degreasing sintering furnace and a wax catching tank group, wherein the vacuum degreasing sintering furnace comprises a furnace barrel body, an effective heating area which is arranged in the furnace barrel body and is formed by surrounding of a heat insulation layer, a scattering area which is formed by the heat insulation layer and the inner wall of the furnace barrel body, and a wax catching pipeline which penetrates through the heat insulation layer and the furnace barrel body, one end of the wax catching pipeline is communicated with the effective heating area, the other end of the wax catching pipeline is communicated with the wax catching tank group, and the vacuum degreasing sintering forming method comprises the following steps:
1) feeding: placing a blank to be sintered into an effective heating area of the vacuum degreasing sintering furnace:
2) vacuumizing: vacuumizing the vacuum degreasing sintering furnace and the wax catching tank group until a set pressure value is reached;
the set pressure value is 5-20 Pa;
3) degreasing: introducing a current-carrying gas into the vacuum degreasing sintering furnace, heating and vacuumizing according to a preset degreasing heating curve, detecting the air pressure of the overflow area and the air pressure of the wax catching tank group, adjusting the flow rate of the current-carrying gas and adjusting the vacuum degree of the wax catching tank group according to the difference value between the air pressure of the overflow area and the air pressure of the wax catching tank group so as to keep the difference value between the air pressure of the overflow area and the air pressure of the wax catching tank group within a set pressure difference range, and allowing vapor wax generated in the effective heating area to enter the wax catching tank group along with the current-carrying gas through the wax catching pipeline;
the air pressure of the overflow area is greater than that of the wax catching tank group, and the set pressure difference range is 10-30 KPa;
4) sintering at high temperature;
5) and (6) cooling.
2. The vacuum degreasing sintering forming method of claim 1, wherein the vacuum degreasing sintering system comprises a vacuum pump set, one end of the vacuum pump set is communicated with the wax catching tank set and is used for vacuumizing the furnace cylinder body through the wax catching tank set, the other end of the vacuum pump set is connected with the furnace cylinder body and is used for introducing gas into the furnace cylinder body, and the vacuum degree of the wax catching tank set is adjusted by adjusting the size of a valve of the vacuum pump set.
3. The vacuum degreasing sintering molding method according to claim 1 or 2, wherein the degreasing temperature rise curve is: heating the mixture from room temperature to 500-600 ℃ at a heating rate of 1-5 ℃/min, and preserving the heat for 1-2 hours.
4. The vacuum degreasing sintering molding method according to claim 1 or 2, wherein in the high-temperature sintering stage, after the degreasing stage is finished, the temperature is raised to 1100-1500 ℃ at a temperature rise rate of 5-20 ℃/min, and the temperature is maintained for 1-2 hours.
5. The vacuum degreasing sintering molding method as claimed in claim 4, wherein the high-temperature sintering stage further comprises stopping the introduction of the carrier gas after the degreasing stage is finished, and introducing a protective gas with a preset flow rate after the degreasing stage is vacuumized to a target pressure value.
6. The vacuum degreasing sintering molding method according to claim 1 or 2, wherein the carrier gas is one of an inert gas, hydrogen gas, or nitrogen gas.
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| CN117232283B (en) * | 2023-11-15 | 2024-01-19 | 湘潭新大粉末冶金技术有限公司 | Automatic start-stop system of intelligent vacuum dewaxing sintering furnace |
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