CN106975278B - Method and device for circularly purifying impurity gas in low-positive-pressure sealing forming chamber - Google Patents
Method and device for circularly purifying impurity gas in low-positive-pressure sealing forming chamber Download PDFInfo
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- CN106975278B CN106975278B CN201710245334.9A CN201710245334A CN106975278B CN 106975278 B CN106975278 B CN 106975278B CN 201710245334 A CN201710245334 A CN 201710245334A CN 106975278 B CN106975278 B CN 106975278B
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D46/56—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours with multiple filtering elements, characterised by their mutual disposition
- B01D46/62—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours with multiple filtering elements, characterised by their mutual disposition connected in series
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D46/30—Particle separators, e.g. dust precipitators, using loose filtering material
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Abstract
The invention discloses a method and a device for circularly purifying impurity gas in a low-positive-pressure sealed forming chamber; the device comprises a forming chamber and a gas circulating and purifying system thereof, wherein the gas circulating and purifying system is controlled by a computer; a gas circulation outlet A and a gas circulation inlet B are respectively arranged at two ends of the inner cavity of the forming chamber; the gas circulation purification system comprises a gas distribution device, a filter box, an activated carbon filter box, a circulation gas circuit formed by a circulation gas pump, a differential pressure sensor and the like; two pressure guide ports of the pressure difference sensor are respectively connected with an outlet pipeline of the filter box, an inlet pipeline of the circulating air pump and an inlet pipeline of the gas uniform distribution device; the device has higher purification efficiency, can quickly adjust various indexes of the environment of the forming chamber, such as oxygen content, air pressure, metal dust particle concentration and the like, and has high purification degree on the metal dust particles in the environment of the forming chamber.
Description
Technical Field
The invention relates to the field of Selective Laser Melting (SLM) additive manufacturing, in particular to a method and a device for circularly purifying impurity gas in a low-positive-pressure sealed forming chamber.
Background
With the development of Selective Laser Melting (SLM) technology, the SLM has been capable of directly manufacturing metal parts with metallurgical bonding, compact structure, high dimensional accuracy and good mechanical properties, and can mold small-batch and personalized metal parts with complex surfaces and internal structures, thereby having broad application prospects and becoming a research hotspot in the current additive manufacturing field.
The control of the gas environment in the sealed forming chamber during the SLM processing is very important, wherein the key indicators are oxygen content, gas pressure, metal dust particle concentration. Wherein, the oxygen content is directly related to the forming quality of the formed metal parts, and has great influence on the comprehensive performance of the metal parts. The oxygen content in the forming chamber for selective laser melting needs to be kept low so as to prevent the metal parts in the forming from being oxidized and influencing the performance of the parts. During the molding process, a low positive pressure environment of 10Kpa should be maintained in the sealed molding chamber to ensure that external oxygen cannot penetrate into the sealed molding chamber. Pollution and leakage of metal dust particles in a gas environment are also a key problem to be solved, and the dust particles influence laser irradiation, light transmittance of optical lenses and even melting and solidification stability of a molten pool. Generally, the grain size of the metal materials used by the SLM, such as 316L stainless steel, CoCrMo alloy and titanium alloy, is only dozens of microns, the size of the metal splashes generated in the SLM forming process is smaller, and the powder and splashes are easily scattered on the forming surface of the metal and are dispersed in the air for a long time, which not only affects the performance of the formed metal parts, but also seriously threatens the personal safety of operators. In addition, the existing gas filtering device applied to the SLM system has some defects: the cleanliness of the gas obtained by adopting a pure HEPA filter screen (high-efficiency air filter screen) filtering mode is not high enough; the cleaning and collecting process of the metal dust collected by the HEPA filter screen is not convenient enough, and a great improvement space is provided; due to factors such as air inlet mode and the like, the phenomena of local blockage and abrasion of the filter screen are serious, and the service life of the filter screen is short; the sealing performance of the existing gas circulation purification device is not good enough, and metal dust in the working space inside the device can be disturbed by external air flow and spread to a forming cavity of SLM equipment or external air, so that the SLM processing process, the human health and the like are influenced.
Therefore, a novel low-positive-pressure circulation purification method and device for impurity gas in a sealed forming chamber are needed, the purification effect of the impurity gas is improved, and real-time monitoring feedback is carried out on some key indexes of the purification device in the operation process.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method and a device for circularly purifying impurity gas in a low-positive-pressure sealing forming chamber. The gas circulation purification process in the SLM sealed forming chamber is comprehensively controlled, so that the oxygen concentration, the air pressure and the metal dust particle concentration in the environment of the sealed forming chamber meet the specified requirements, and the forming quality of the SLM formed metal part is improved.
The invention is realized by the following technical scheme:
a low positive pressure seal forming indoor impurity gas circulation purification device comprises a forming chamber 1 and a gas circulation purification system thereof, wherein the gas circulation purification system is controlled by a computer 7; a gas circulation outlet A and a gas circulation inlet B are respectively formed at two ends of the inner cavity of the forming chamber 1;
the gas circulating and purifying system comprises a first one-way gas valve 16, a three-way pipe 14, a gas uniform distribution device 15, a filter box 17, an activated carbon filter box 20, a circulating gas pump 9, a second one-way gas valve 8, a first differential pressure sensor 10 and a second differential pressure sensor 11;
the gas circulation outlet A is sequentially connected with a first one-way gas valve 16, a three-way pipe 14, a gas uniform distribution device 15, a filter box 17, an activated carbon filter box 20, a circulating gas pump 9, a second one-way gas valve 8 and a gas circulation inlet B through pipelines;
two pressure guide ports of the first differential pressure sensor 10 are respectively connected with two measuring points, a first measuring point is connected to an outlet pipeline of the filter box 17, and a second measuring point is connected to an inlet pipeline of the circulating air pump 9;
two pressure guide ports of the second differential pressure sensor 11 are respectively connected with two measuring points, a first measuring point is connected to an inlet pipeline of the gas uniform distribution device 15, and a second measuring point is connected to an outlet pipeline of the filter box 17;
and the signal control end of the first differential pressure sensor 10, the signal control end of the second differential pressure sensor 11 and the circulating air pump 9 are respectively connected with the computer 7.
The gas uniform distribution device 15 comprises a shell 15-3 and a gas inlet 15-1, wherein a plurality of gas inlet partition plates 15-2 are arranged in the shell 15-3, and the gas inlet partition plates 15-2 equally divide the inside of the shell 15-3 into a plurality of fan-shaped gas outlet channels 15-4; the air inlet 15-1 is connected with the three-way pipe 14, and the fan-shaped air outlet channel 15-4 is connected with the inlet of the activated carbon filter box 20 through a pipeline;
when the airflow containing metal dust particles is uniformly distributed to each fan-shaped air outlet channel through the air inlet 15-1, the airflow enters the filter box 17 under the distribution effect of each fan-shaped air outlet channel and uniformly passes through the HEPA filter element 18.
An HEPA filter element 18 is arranged in the filter box 17, and an electrostatic discharge net 19 is arranged on the surface of the HEPA filter element 18; the HEPA filter element 18 is used for carrying out primary filtration on the gas containing the metal dust particles passing through the first one-way gas valve 16; the static releasing net 19 is made of a plurality of metal concentric rings and axial conductive wires connected with the metal concentric rings through spot welding, and the static releasing net 19 is used for rapidly releasing static on each part of the surface of the HEPA filter element 18.
A collecting bottle 12 with a valve 13 is further connected to one port of the three-way pipe 14 and is used for collecting impurity particles accumulated on the surface of the HEPA filter element 18 and falling; the valve 13 is normally closed and when it is desired to clean the HEPA filter 18, the valve 13 is opened to allow the passage of foreign particles into the collection bottle 12 for centralized disposal.
An oxygen content sensor 2 and an air pressure sensor 3 are arranged at the top of the forming chamber 1; which are used to feed back the oxygen content and pressure data in the forming chamber 1 to the computer 7, respectively.
The gas circulation purification system also comprises a vacuum pump 4 for pumping out the gas mixed with oxygen in the forming chamber 1 so as to prevent the oxygen in the forming chamber 1 from generating oxidation with parts in the processing process.
The forming chamber 1 is also connected with a protective gas supply device arranged outside to prevent the oxidation of parts in the processing process; the protective gas supply device comprises a protective gas bottle 6 and an electromagnetic valve 5; the protective gas bottle 6 is connected with the forming chamber 1 through a solenoid valve 5.
The second one-way gas valve 8 and the first one-way gas valve 16 are identical in structure and respectively comprise a shell 8-1, a spring fixing frame 8-2 with holes, a spring 8-3 and an air inlet piston 8-4;
the spring fixing frame 8-2 divides the interior of the shell 8-1 into two parts, one end of the spring 8-3 is propped against the spring fixing frame 8-2, and the other end of the spring 8-3 is propped against an air inlet piston 8-4 arranged at an air inlet of the shell 8-1; when the airflow containing metal dust particles from the forming chamber 1 pushes the air inlet piston 8-4 to overcome the thrust of the spring 8-3, the airflow flows out of the air outlet of the shell 8-1; when the airflow from the air inlet of the shell 8-1 disappears, the air inlet piston 8-4 resets and seals the air inlet under the elastic force of the spring 8-3, and unidirectional air inlet is realized.
An operation method of a low-positive-pressure sealed forming indoor impurity gas circulating purification device comprises the following steps:
the method comprises the following steps: protective gas is introduced while the vacuum pump is started
After receiving a starting command of a gas circulation purification process, the computer 7 sends a signal to start the vacuum pump 4 and simultaneously opens the electromagnetic valve 5 to connect the protective gas cylinder 6; the vacuum pump 4 is used for pumping out the gas mixed with the oxygen in the forming chamber 1; the protective gas bottle 6 is responsible for filling inert protective gas into the forming chamber 1 and constantly diluting the oxygen concentration in the forming chamber 1; the vacuum pump 4 is started and the inert protective gas is introduced at the same time, so that the reduction rate of the oxygen concentration in the forming chamber 1 can be accelerated;
step two: detecting whether the oxygen content is lower than 100ppm
The oxygen content sensor 2 sends the detected oxygen concentration data in the forming chamber 1 to the computer 7 in real time, and the computer 7 detects whether the oxygen concentration is lower than the threshold value of 100 ppm; if the oxygen concentration is higher than 100ppm, the working states of the vacuum pump 4 and the introduced inert protective gas are continuously kept, and the oxygen concentration is continuously reduced until the threshold value is reached; if the oxygen concentration is lower than 100ppm, closing the vacuum pump 4, keeping the electromagnetic valve 5 in an open state, and continuously filling inert protective gas into the forming chamber 1 to improve the air pressure in the forming chamber 1;
step three: detecting whether the air pressure reaches 10Kpa
The air pressure sensor 3 sends air pressure data in the molding chamber 1 to the computer 7 in real time, and the computer 7 detects that the pressure reaches a threshold value of 10 Kpa; if the pressure is lower than the threshold value, the solenoid valve 5 is continuously opened to keep the supply of the inert protective gas until the pressure detected by the computer 7 reaches the threshold value, so that the low positive pressure state is maintained in the molding chamber 1; if the air pressure is higher than 10Kpa, the electromagnetic valve 5 is closed, and the supply of the inert protective gas is cut off;
step four: starting gas circulation purification
Starting the first differential pressure sensor 10 and the second differential pressure sensor 11, reading the air pressure difference between the HEPA filter element 18 and the two sides of the activated carbon filter box 20 in real time, and transmitting the differential pressure data to the computer 7;
the airflow containing metal dust particles from the forming chamber 1 is uniformly distributed to each fan-shaped air outlet channel 15-4 through an air inlet 15-1 of an air uniform distribution device 15, enters a filter box 17 under the guidance of the cavity wall of each fan-shaped air outlet channel, uniformly passes through the surface of an HEPA filter element 18, and completes the primary filtration of the metal dust in the airflow at the HEPA filter element 18 to filter most impurities; meanwhile, the static electricity releasing net 19 tightly contacted with the HEPA filter element 18 can quickly release static electricity accumulation generated by friction between the metal dust airflow and the surface of the HEPA filter element 18; the cleaner gas after the primary filtration passes through the activated carbon filter box 20 to complete the secondary filtration of the gas, and the cleanliness of the gas flow is continuously improved; the clean gas after two-stage filtration is sent back to the forming chamber 1 through the second one-way gas valve 8 under the driving of the circulating air pump 9, and one-time gas circulation action is completed.
In the process of the gas circulation work in the step four, the first differential pressure sensor 10 and the second differential pressure sensor 11 are respectively used for detecting the pressure difference of two sides of the HEPA filter element 18 and the active carbon filter box 20 in real time and transmitting the pressure difference data to the computer 7; when the air pressure difference is greater than or less than a specified value, the HEPA filter screen 18 and the activated carbon filter box 20 are respectively blocked or damaged, the computer 7 stops the circulating air pump 9 in time, the air circulating work is suspended, and meanwhile an alarm signal is sent to prompt personnel to clean or replace the HEPA filter screen 18.
Compared with the prior art, the invention has the following advantages and effects:
the invention can comprehensively control three indexes of oxygen concentration, air pressure and metal dust particle concentration in the SLM sealed forming chamber to meet the requirements, thereby improving the forming quality of SLM formed metal parts.
The gas circulation purification system adopts a combined filtration mode of the HEPA filter screen and the activated carbon filter box, so that cleaner gas after primary filtration is filtered and secondary filtration of airflow is completed through the activated carbon filter box, and the filtration efficiency is improved.
The gas circulation purification system adopts the filter element gas uniform distribution device, is used for shunting the impurity-containing gas flow and enabling the impurity-containing gas flow to uniformly pass through the HEPA filter screen through the unique design of the internal gas passage, avoids the selective nonuniform passing of the dust gas flow through the HEPA filter screen, lightens the rapid accumulation and blockage of dust at the local part of the filter screen and the abrasion of the filter screen, and prolongs the service life of the filter screen. Simultaneously, the slope structural design of inner chamber also helps metal dust to rely on self gravity to roll to the dust collecting bottle in, has improved the collection efficiency of metal dust.
The static electricity releasing net adopted by the gas circulation purifying system is a network structure consisting of a plurality of metal concentric rings and the rings, so that the static electricity of all parts on the surface of the HEPA filter screen can be conveniently and quickly released, and metal dust can be prevented from exploding.
The pressure difference sensor adopted by the gas circulation purification system obtains the working state of the corresponding part in real time by detecting the pressure difference between the HEPA filter screen, the activated carbon filter box and the air inlet and outlet of the three-phase motor in real time, and transmits the data to the controller through the data line, and the controller outputs the measured data to the display. Reminding workers to check and eliminate problems in time.
In conclusion, the device has higher purification efficiency, can quickly adjust a plurality of indexes such as oxygen content, air pressure and metal dust particle concentration in the environment of the forming chamber, and has high purification degree on the metal dust particles in the environment of the forming chamber. This device filter long service life has advantages such as secondary filter, dust are collected, electrostatic discharge is convenient, the real-time is good, can conveniently acquire the situation of each key position, locks relevant problem, maintains the good running state of device, improves gaseous circulation purification efficiency.
Drawings
FIG. 1 is a schematic structural view of an impurity gas circulation purification device in a low-positive-pressure sealing forming chamber of the invention.
FIG. 2 is a top view of the gas distribution apparatus of the present invention.
Fig. 3 is a sectional view taken along line a-a of fig. 2.
Fig. 4 is a sectional view taken along the direction of fig. 2B-B.
FIG. 5 is a three-dimensional view of the gas distribution apparatus of the present invention.
Figure 6 is a schematic view of a one-way gas valve of the present invention.
Fig. 7 is a flow chart of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Examples
As shown in fig. 1 to 7. The invention discloses a low-positive pressure sealed forming chamber impurity gas circulation purification device, which comprises a forming chamber 1 and a gas circulation purification system thereof, wherein the gas circulation purification system is controlled by a computer 7; a gas circulation outlet A and a gas circulation inlet B are respectively formed at two ends of the inner cavity of the forming chamber 1;
the gas circulating and purifying system comprises a first one-way gas valve 16, a three-way pipe 14, a gas uniform distribution device 15, a filter box 17, an activated carbon filter box 20, a circulating gas pump 9, a second one-way gas valve 8, a first differential pressure sensor 10 and a second differential pressure sensor 11;
the gas circulation outlet A is sequentially connected with a first one-way gas valve 16, a three-way pipe 14, a gas uniform distribution device 15, a filter box 17, an activated carbon filter box 20, a circulating gas pump 9, a second one-way gas valve 8 and a gas circulation inlet B through pipelines;
two pressure guide ports of the first differential pressure sensor 10 are respectively connected with two measuring points, a first measuring point is connected to an outlet pipeline of the filter box 17, and a second measuring point is connected to an inlet pipeline of the circulating air pump 9;
two pressure guide ports of the second differential pressure sensor 11 are respectively connected with two measuring points, a first measuring point is connected to an inlet pipeline of the gas uniform distribution device 15, and a second measuring point is connected to an outlet pipeline of the filter box 17;
and the signal control end of the first differential pressure sensor 10, the signal control end of the second differential pressure sensor 11 and the circulating air pump 9 are respectively connected with the computer 7.
The gas uniform distribution device 15 comprises a shell 15-3 and a gas inlet 15-1, wherein a plurality of gas inlet partition plates 15-2 are arranged in the shell 15-3, and the gas inlet partition plates 15-2 equally divide the interior of the shell 15-3 into a plurality of fan-shaped gas outlet channels 15-4; the air inlet 15-1 is connected with the three-way pipe 14, and the fan-shaped air outlet channel 15-4 is connected with the inlet of the activated carbon filter box 20 through a pipeline;
when the airflow containing metal dust particles is uniformly distributed to each fan-shaped air outlet channel through the air inlet 15-1, the airflow enters the filter box 17 under the distribution effect of each fan-shaped air outlet channel and uniformly passes through the HEPA filter element 18.
An HEPA filter element 18 is arranged in the filter box 17, and an electrostatic discharge net 19 is arranged on the surface of the HEPA filter element 18; the HEPA filter element 18 is used for filtering the gas containing the metal dust particles passing through the first one-way gas valve 16 for the first time; the static electricity releasing net 19 is made of a plurality of metal concentric circular rings and axial conducting wire spot welding connected with the metal concentric circular rings, and the static electricity releasing net 19 is used for rapidly releasing static electricity on each part of the surface of the HEPA filter element 18. The HEPA in the HEPA cartridge 18 is efficient particulate gas filtration.
A collecting bottle 12 with a valve 13 is connected to one port of the three-way pipe 14 and is used for collecting impurity particles which are gathered on the surface of the HEPA filter element 18 and fall; the valve 13 is normally closed and when it is desired to clean the HEPA filter 18, the valve 13 is opened to allow the passage of foreign particles into the collection bottle 12 for centralized disposal.
An oxygen content sensor 2 and an air pressure sensor 3 are arranged at the top of the forming chamber 1; which are used to feed back the oxygen content and pressure data in the forming chamber 1 to the computer 7, respectively.
The gas circulation purification system also comprises a vacuum pump 4 for pumping out the gas mixed with oxygen in the forming chamber 1 so as to prevent the oxygen in the forming chamber 1 from generating oxidation with parts in the processing process.
The forming chamber 1 is also connected with a protective gas supply device arranged outside to prevent the oxidation of parts in the processing process; the protective gas supply device comprises a protective gas bottle 6 and an electromagnetic valve 5; the protective gas bottle 6 is connected with the forming chamber 1 through a solenoid valve 5. The protective gas can adopt Ar, N 2 So as to protect the SLM processing process and prevent the oxidation of parts in the processing process.
The second one-way gas valve 8 and the first one-way gas valve 16 are identical in structure and respectively comprise a shell 8-1, a spring fixing frame 8-2 with holes, a spring 8-3 and an air inlet piston 8-4;
the spring fixing frame 8-2 divides the interior of the shell 8-1 into two parts, one end of the spring 8-3 is propped against the spring fixing frame 8-2, and the other end of the spring 8-3 is propped against an air inlet piston 8-4 arranged at an air inlet of the shell 8-1; when the airflow containing the metal dust particles from the forming chamber 1 pushes the air inlet piston 8-4 to overcome the thrust of the spring 8-3, the airflow flows out of the air outlet of the shell 8-1; when the airflow from the air inlet of the shell 8-1 disappears, the air inlet piston 8-4 resets and seals the air inlet under the elastic force action of the spring 8-3, and unidirectional air inlet is realized.
The operation method of the impurity gas circulation purification device in the low-positive-pressure sealing forming chamber can be realized by the following steps:
the method comprises the following steps: protective gas is introduced while the vacuum pump is started
After receiving a starting command of a gas circulation purification process, the computer 7 sends a signal to start the vacuum pump 4 and simultaneously opens the electromagnetic valve 5 to connect the protective gas cylinder 6; the vacuum pump 4 is used for pumping out the gas mixed with oxygen in the forming chamber 1; the protective gas bottle 6 is responsible for filling inert protective gas into the forming chamber 1 and constantly diluting the oxygen concentration in the forming chamber 1; the vacuum pump 4 is started and the inert protective gas is introduced at the same time, so that the reduction rate of the oxygen concentration in the forming chamber 1 can be accelerated;
step two: detecting whether the oxygen content is lower than 100ppm
The oxygen content sensor 2 sends the detected oxygen concentration data in the forming chamber 1 to the computer 7 in real time, and the computer 7 detects whether the oxygen concentration is lower than the threshold value of 100 ppm; if the oxygen concentration is higher than 100ppm, the working state of the vacuum pump 4 and the inert protective gas is continuously kept, and the oxygen concentration is continuously reduced until the threshold value is reached; if the oxygen concentration is lower than 100ppm, closing the vacuum pump 4, keeping the electromagnetic valve 5 in an opening state, and continuously filling inert protective gas into the forming chamber 1 to improve the air pressure in the forming chamber 1;
step three: detecting whether the air pressure reaches 10Kpa, the low positive pressure critical value in the forming chamber 1 can be set, and is generally 10-50Kpa
The air pressure sensor 3 sends the air pressure data in the forming chamber 1 to the computer 7 in real time, and the computer 7 detects that the pressure reaches the threshold value of 10 Kpa; if the pressure is lower than the threshold value, the solenoid valve 5 is opened continuously to keep the supply of inert protective gas until the pressure detected by the computer 7 reaches the threshold value, so that the low positive pressure state is maintained in the forming chamber 1; if the air pressure is higher than 10Kpa, the electromagnetic valve 5 is closed, and the supply of the inert protective gas is cut off;
step four: starting gas circulation purification
Starting the first differential pressure sensor 10 and the second differential pressure sensor 11, reading the air pressure difference of the two sides of the HEPA filter element 18 and the activated carbon filter box 20 in real time, and transmitting the differential pressure data to the computer 7;
the airflow containing metal dust particles from the forming chamber 1 is uniformly distributed to each fan-shaped air outlet channel 15-4 through an air inlet 15-1 of an air uniform distribution device 15, enters a filter box 17 under the guidance of the wall of each fan-shaped air outlet channel, uniformly passes through the surface of an HEPA filter element 18, completes one-time filtration of the metal dust in the airflow at the HEPA filter element 18, and filters most of impurities; meanwhile, the static electricity releasing net 19 tightly contacted with the HEPA filter element 18 can quickly release static electricity accumulation generated by friction between the metal dust airflow and the surface of the HEPA filter element 18; the cleaner gas after the primary filtration passes through the activated carbon filter box 20 to complete the secondary filtration of the gas, and the cleanliness of the gas flow is continuously improved; the clean gas after two-stage filtration is sent back to the forming chamber 1 through the second one-way gas valve 8 under the driving of the circulating air pump 9, and one-time gas circulation action is completed.
In the process of the gas circulation work in the step four, the first differential pressure sensor 10 and the second differential pressure sensor 11 are respectively used for detecting the pressure difference of two sides of the HEPA filter element 18 and the active carbon filter box 20 in real time and transmitting the pressure difference data to the computer 7; when the air pressure difference is greater than or less than a specified value, the HEPA filter screen 18 and the activated carbon filter box 20 are respectively blocked or damaged, the computer 7 stops the circulating air pump 9 in time, the air circulating work is suspended, and meanwhile an alarm signal is sent to prompt personnel to clean or replace the HEPA filter screen 18.
As described above, the present invention can be preferably realized.
The present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents and fall within the scope of the present invention.
Claims (8)
1. A low positive pressure seal forming chamber impurity gas circulation purification device comprises a forming chamber (1) and a gas circulation purification system thereof, wherein the gas circulation purification system is controlled by a computer (7); the method is characterized in that: a gas circulation outlet A and a gas circulation inlet B are respectively formed at two ends of the inner cavity of the forming chamber (1);
the gas circulating and purifying system comprises a first one-way gas valve (16), a three-way pipe (14), a gas uniform distribution device (15), a filter box (17), an activated carbon filter box (20), a circulating gas pump (9), a second one-way gas valve (8), a first differential pressure sensor (10) and a second differential pressure sensor (11);
the gas circulation outlet A is sequentially connected with a first one-way gas valve (16), a three-way pipe (14), a gas uniform distribution device (15), a filter box (17), an activated carbon filter box (20), a circulating gas pump (9), a second one-way gas valve (8) and a gas circulation inlet B through pipelines;
two pressure guide ports of the first differential pressure sensor (10) are respectively connected with two measuring points, the first measuring point is connected to an outlet pipeline of the filter box (17), and the second measuring point is connected to an inlet pipeline of the circulating air pump (9);
two pressure guide ports of the second differential pressure sensor (11) are respectively connected with two measuring points, a first measuring point is connected to an inlet pipeline of the gas uniform distribution device (15), and a second measuring point is connected to an outlet pipeline of the filter box (17);
the signal control end of the first differential pressure sensor (10), the signal control end of the second differential pressure sensor (11) and the circulating air pump (9) are respectively connected with a computer (7);
the gas uniform distribution device (15) comprises a shell (15-3) and a gas inlet (15-1), wherein a plurality of gas inlet partition plates (15-2) are arranged in the shell (15-3), and the gas inlet partition plates (15-2) equally divide the interior of the shell (15-3) into a plurality of fan-shaped gas outlet channels (15-4); the air inlet (15-1) is connected with a three-way pipe (14), and the fan-shaped air outlet channel (15-4) is connected with an inlet of the activated carbon filter box (20) through a pipeline;
when the airflow containing the metal dust particles is uniformly distributed to each fan-shaped air outlet channel through the air inlet (15-1), the airflow enters the filter box (17) under the distribution action of each fan-shaped air outlet channel and uniformly passes through the HEPA filter element (18);
an HEPA filter element (18) is arranged in the filter box (17), and a static electricity release net (19) is arranged on the surface of the HEPA filter element (18); the HEPA filter element (18) is used for filtering the gas containing the metal dust particles passing through the first one-way gas valve (16) for the first time; the static electricity releasing net (19) is made of a plurality of metal concentric rings and axial conducting wires connected with the metal concentric rings through spot welding, and the static electricity releasing net (19) is used for rapidly releasing static electricity on each part of the surface of the HEPA filter element (18).
2. The indoor impurity gas circulation purifier of low positive pressure seal forming of claim 1, characterized by: a collecting bottle (12) with a valve (13) is further connected to one port of the three-way pipe (14) and is used for collecting impurity particles which are gathered on the surface of the HEPA filter element (18) and fall; the valve (13) is closed at daily time, and when the HEPA filter element (18) needs to be cleaned, the valve (13) is opened to enable the impurity particles to enter the collecting bottle (12) for centralized treatment.
3. The indoor impurity gas circulation purifier of low-positive pressure seal shaping of claim 2, characterized by: the top of the forming chamber (1) is provided with an oxygen content sensor (2) and an air pressure sensor (3); they are each used to feed back oxygen content and pressure data in the forming chamber (1) to the computer (7).
4. The circulation purification device for impurity gas in the low positive pressure sealing forming chamber according to any one of claims 1 to 3, wherein: the gas circulation purification system also comprises a vacuum pump (4) for pumping out gas mixed with oxygen in the forming chamber (1) so as to prevent the oxygen in the forming chamber (1) from generating oxidation with parts in the processing process.
5. The indoor impurity gas circulation purifier of low-positive pressure seal shaping of claim 4, characterized by: the forming chamber (1) is also connected with an external protective gas supply device to prevent the oxidation of parts in the processing process; the protective gas supply device comprises a protective gas bottle (6) and an electromagnetic valve (5); the protective gas bottle (6) is connected with the forming chamber (1) through a solenoid valve (5) by a pipeline.
6. The indoor impurity gas circulation purifier of low positive pressure seal forming of claim 5, characterized by: the second one-way gas valve (8) and the first one-way gas valve (16) are identical in structure and respectively comprise a shell (8-1), a spring fixing frame (8-2) with holes, a spring (8-3) and an air inlet piston (8-4);
the spring fixing frame (8-2) divides the interior of the shell (8-1) into two parts, one end of the spring (8-3) is propped against the spring fixing frame (8-2), and the other end of the spring (8-3) is propped against an air inlet piston (8-4) arranged at an air inlet of the shell (8-1); when the airflow containing the metal dust particles from the forming chamber (1) pushes the air inlet piston (8-4) to overcome the thrust of the spring (8-3), the airflow flows out of the air outlet of the shell (8-1); when the airflow from the air inlet of the shell (8-1) disappears, the air inlet piston (8-4) resets and seals the air inlet under the elastic force of the spring (8-3), and unidirectional air inlet is realized.
7. An operation method of an indoor impurity gas circulation purification device for low-positive-pressure sealing forming is characterized by comprising the following steps:
the method comprises the following steps: starting the vacuum pump and simultaneously introducing protective gas
After receiving a starting command of a gas circulation purification process, a computer (7) sends a signal to start a vacuum pump (4) and simultaneously opens an electromagnetic valve (5) to connect a protective gas cylinder (6); the vacuum pump (4) is used for pumping out the gas mixed with oxygen in the forming chamber (1); the protective gas bottle (6) is responsible for filling inert protective gas into the forming chamber (1) and constantly diluting the oxygen concentration in the forming chamber (1); the vacuum pump (4) is started and the inert protective gas is introduced at the same time, so that the reduction rate of the oxygen concentration in the forming chamber (1) can be accelerated;
step two: detecting whether the oxygen content is lower than 100ppm
The oxygen content sensor (2) sends detected oxygen concentration data in the forming chamber (1) to the computer (7) in real time, and the computer (7) detects whether the oxygen concentration is lower than a threshold value of 100 ppm; if the oxygen concentration is higher than 100ppm, the working state of the vacuum pump (4) and the inert protective gas is continuously kept, and the oxygen concentration is continuously reduced until the threshold value is reached; if the oxygen concentration is lower than 100ppm, closing the vacuum pump (4), keeping the electromagnetic valve (5) in an open state, and continuously filling inert protective gas into the forming chamber (1) to improve the air pressure in the forming chamber (1);
step three: detecting whether the air pressure reaches 10Kpa
The air pressure sensor (3) sends air pressure data in the forming chamber (1) to the computer (7) in real time, and the computer (7) detects that the pressure reaches a threshold value of 10 Kpa; if the pressure is lower than the threshold value, the electromagnetic valve (5) is continuously opened to keep the supply of the inert protective gas until the pressure detected by the computer (7) reaches the threshold value, so that the low positive pressure state is maintained in the forming chamber (1); if the air pressure is higher than 10Kpa, closing the electromagnetic valve (5) and cutting off the supply of the inert protective gas;
step four: starting gas circulation purification
Starting a first differential pressure sensor (10) and a second differential pressure sensor (11), reading the air pressure difference of two sides of an HEPA filter element (18) and an active carbon filter box (20) in real time, and transmitting the differential pressure data to a computer (7);
the airflow containing metal dust particles in the forming chamber 1 is uniformly distributed to each fan-shaped air outlet channel (15-4) through an air inlet (15-1) of an air uniform distribution device (15), enters a filter box (17) under the guidance of the wall of each fan-shaped air outlet channel, uniformly passes through the surface of a HEPA filter element (18), and finishes primary filtration of the metal dust in the airflow at the HEPA filter element (18); meanwhile, the static electricity release net (19) which is in close contact with the HEPA filter element (18) can quickly release static electricity accumulation generated by friction between the metal dust airflow and the surface of the HEPA filter element (18); the gas after primary filtration passes through an active carbon filter box (20) to finish secondary filtration of the gas, and the cleanliness of the gas flow is continuously improved; the clean gas after two-stage filtration is sent back to the forming chamber (1) through a second one-way gas valve (8) under the driving of a circulating gas pump (9), and a gas circulating action is completed.
8. The operation method of the impurity gas circulation purification device in the low positive pressure seal forming chamber according to claim 7, wherein in the four-step gas circulation operation process, the first differential pressure sensor (10) and the second differential pressure sensor (11) are respectively used for detecting the gas pressure difference at two sides of the HEPA filter element (18) and the activated carbon filter box (20) in real time and transmitting the pressure difference data to the computer (7); when the air pressure difference is greater than or less than a specified value, the HEPA filter screen 18 and the activated carbon filter box (20) are respectively blocked or damaged, the computer (7) stops the circulating air pump (9) in time, the air circulation work is suspended, and meanwhile an alarm signal is sent to prompt personnel to clean or replace the HEPA filter element (18).
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| CN110095566B (en) * | 2018-01-31 | 2022-06-10 | 研能科技股份有限公司 | Gas detection device |
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| CN203744498U (en) * | 2014-03-18 | 2014-07-30 | 童军 | Air purification and filtration assembly for indoor air conditioner |
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