Parallel double-filter-element dust removal system for SLM (selective laser melting) equipment

Abstract

The utility model relates to the technical field of additive manufacturing equipment, and discloses a parallel double-filter-element dust removal system for SLM (selective laser melting) equipment, an air outlet of a forming chamber is connected with a first filter module through an air outlet pipeline, the first filter module comprises an air purification chamber and a dust air chamber which are arranged up and down, the air purification chamber is communicated with a recovery pipeline, and the dust air chamber is communicated with the air outlet pipeline; a partition plate is arranged between the air purification chamber and the dust air chamber, at least one air vent penetrates through the partition plate, a filter element is arranged below the air vent, and the air purification chamber is connected with a back-blowing ash removal device which conducts back-blowing dust removal on the filter element through the air vent. The filter element in the first filter module can capture smoke dust in the inert gas, so that the smoke dust is blocked on the outer surface of the filter element, and the smoke dust is prevented from influencing the quality of a workpiece. When a certain amount of smoke dust is accumulated on the outer surface of the filter element in the first filter module, the filter element can be subjected to back-blowing dust removal operation through the back-blowing dust removal device, so that the smoke dust adsorbed on the outer surface of the filter element is removed.

Description

Technical Field

[0001] The utility model relates to the technical field of additive manufacturing equipment, and in particular to a parallel double-filter dust removal system for SLM equipment. Background Art

[0002] SLM: Selective laser melting is a major technical approach in the additive manufacturing of metal materials. This technology uses laser as the energy source, and scans the metal powder bed layer by layer according to the path planned in the three-dimensional CAD slice model. The scanned metal powder is melted and solidified to achieve the effect of metallurgical bonding, and finally the metal parts designed by the model are obtained. Specifically, before printing, the laser system will receive the contour data of the current layer, and the Z axis will drop to a specified height according to the design value. At this time, the powder spreading device evenly spreads the metal powder over the entire printing surface, and the laser scans according to the contour data, and the cycle continues until the workpiece is processed. For example, the utility model patent with announcement number CN114433876B discloses a similar SLM device.

[0003] In order to reduce the risk of fire caused by excessive oxygen content in the molding chamber of the above-mentioned SLM equipment, it is necessary to place the molding chamber in an inert gas protective atmosphere when the equipment is running. However, during the workpiece molding process, the metal powder dust in the powder spreading stage and the smoke generated by powder sintering will affect the propagation of the laser beam and thus affect the quality of the workpiece. In addition, if the smoke is not cleaned up in time, the smoke will remain on the printing surface due to its own gravity. As the metal powder is stacked layer by layer, the smoke will be integrated into the entire workpiece, thereby affecting the performance of the workpiece, so the circulating inert gas needs to be filtered and dusted.

[0004] If you want to remove the smoke and dust in the circulating inert gas, the simplest way is to add a filter in the circulating gas path to block the smoke and dust, so that the clean circulating gas can return to the molding chamber again. However, the traditional dust removal device has the problem of serious loss caused by filter element clogging. In order to ensure the normal operation of the equipment, the filter element needs to be replaced frequently. This not only leads to an increase in the use cost and labor cost, but also reduces the quality of the workpiece, so there is still room for improvement. Utility Model Content

[0005] In view of the shortcomings of the prior art, the utility model provides a parallel dual-filter dust removal system for SLM equipment. The filter element below the air vent is back-blown for dust removal by a back-blowing cleaning device, which can effectively remove smoke and dust accumulated on the outer surface of the filter element to extend the service life of the filter element, thereby reducing the use cost and labor cost caused by frequent replacement of the filter element, and at the same time can improve the quality of the workpiece.

[0006] In order to solve the above technical problems, the utility model is solved by the following technical solutions:

[0007] A parallel dual-filter dust removal system for SLM equipment includes a printer, which includes a molding chamber, an air outlet of the molding chamber is connected to a first filter module through an air outlet duct, the first filter module is connected to the air inlet of the molding chamber through a recovery duct, the first filter module includes a clean air chamber and a dusty air chamber arranged up and down, the clean air chamber is connected to the recovery duct, and the dusty air chamber is connected to the air outlet duct; a partition is arranged between the clean air chamber and the dusty air chamber, at least one air vent penetrates the partition, a power source is arranged on the recovery duct to drive the gas in the molding chamber to run along the air outlet duct, the dusty air chamber, the clean air chamber and the recovery duct in sequence; a filter element is arranged below the air vent, and a back-blowing cleaning device is connected to the clean air chamber to back-blow the filter element through the air vent to remove dust.

[0008] With the above solution, when the inert gas in the molding chamber of the printer is driven by the power source, it passes through the exhaust pipe, dust chamber, clean air chamber and recovery pipe in sequence, and finally returns to the molding chamber, so that the inert gas can circulate. At this time, the filter element in the first filter module can capture the smoke in the inert gas to block the smoke on the outer surface of the filter element, thereby preventing the smoke from affecting the quality of the workpiece. When a certain amount of smoke accumulates on the outer surface of the filter element in the first filter module, the filter element can be backblown and dusted by a backblowing cleaning device to remove the smoke adsorbed on the outer surface of the filter element. In this way, not only can the service life of the filter element be extended, but also the use cost and labor cost of frequent replacement of the filter element can be reduced, and the quality of the workpiece can be improved.

[0009] Preferably, the back-blowing cleaning device includes an air tank inlet valve, a back-blowing air tank and a pulse valve connected in sequence, the other end of the air tank inlet valve is connected to an air source, and the other end of the pulse valve is connected to the top of the clean air chamber. The number of pulse valves is consistent with the filter element, and the connecting ports of the pulse valve and the clean air chamber are aligned with one or more air vents.

[0010] By adopting the above scheme, when the air inlet valve of the air tank is opened, the cooperation of the air source, the back-blowing air tank and the pulse valve can perform a pulsed airflow impact on the filter element below the air vent, thereby improving the back-blowing dust removal effect and stability of the back-blowing cleaning device.

[0011] Preferably, a first ash storage bucket is provided at the bottom of the dust chamber.

[0012] By adopting the above solution, the first ash storage bin can receive the smoke and dust dropped during the back-blowing dust removal of the filter element, thereby facilitating the recovery and cleaning of the smoke and dust, and further improving the operating efficiency and convenience.

[0013] Preferably, a first on-off device is connected between the first ash storage bucket and the bottom of the dust and gas chamber.

[0014] By adopting the above scheme, with the help of the first on-off device, the disassembly and connection between the first ash storage cylinder and the bottom of the dust and gas chamber can be efficiently achieved, while ensuring the stability of the two after being combined.

[0015] Preferably, the inlet and outlet of the first filter module are connected in parallel with a second filter module, the structure of the second filter module is consistent with that of the first filter module, the inlet and outlet of the first filter module are both provided with a second on-off device, and the inlet and outlet of the second filter module are both provided with a third on-off device;

[0016] When the two second on-off devices simultaneously connect the inlet and outlet of the first filter module and the two third on-off devices simultaneously cut off the inlet and outlet of the second filter module, the first filter module enters the operating state and the second filter module enters the waiting state; conversely, when the two second on-off devices simultaneously cut off the inlet and outlet of the first filter module and the two third on-off devices simultaneously connect the inlet and outlet of the second filter module, the first filter module enters the waiting state and the second filter module enters the operating state.

[0017] With the above solution, since the SLM equipment has high requirements for the wind field, the fluctuation of the wind field will cause the smoke and dust to fail to be taken away in time, affecting the propagation of the laser beam, and thus directly affecting the quality of the workpiece. Therefore, it cannot be back-blown online like in industries such as coal mines and lithium batteries. If the pressure difference at both ends of the filter element reaches the threshold, the equipment must be shut down and wait for the back-blowing of the filter element to end. Because metal has the characteristics of thermal expansion and contraction, once the equipment is shut down, the surface temperature of the workpiece will decrease, which means that the volume of the workpiece will decrease. When printing the next layer, the thickness of the powder layer will increase, resulting in poor sintering, which directly affects the mechanical properties of the workpiece. In this solution, when the filter element in one group of filter modules needs to be reversed, the other group of filter modules can be switched to the running state, and the current filter module can be switched to the waiting state. At this time, when the filter element is reversely dusted, the printer and the dust removal system do not need to be shut down. In this way, it can not only improve work efficiency, but also prevent equipment shutdown from causing a decrease in workpiece quality.

[0018] Preferably, a pre-filter device is provided on the air outlet pipe.

[0019] With the above solution, during the workpiece forming process, the smoke and dust generated in the powder spreading stage will also enter the circulating inert gas with the airflow, and the impact of these metal particles on the surface of the filter element is similar to the sandblasting process. Over time, the PTFE coating on the surface of the filter element will be damaged, which will not only affect the reverse dust removal effect, but also the filtering accuracy of the filter element. By installing a pre-filter device, large metal particles in the circulating inert gas can be effectively filtered out, further extending the service life of the filter element.

[0020] Preferably, a post-filtering device is provided on the recovery pipeline.

[0021] With the above solution, as the number of uses and backflush increases, the filter pores of the filter element will gradually expand, resulting in a deterioration in the filtering effect of the filter element. At this time, the post-filter device can effectively intercept the smoke and dust particles that the filter element has not captured, further improving the dust removal effect of the dust removal system.

[0022] Due to the adoption of the above technical solution, the utility model has significant technical effects: when the inert gas in the molding chamber of the printer is driven by the power source, it passes through the exhaust pipe, the dust chamber, the clean air chamber and the recovery pipe in sequence, and finally returns to the molding chamber, so that the inert gas can circulate. At this time, the filter element in the first filter module can capture the smoke in the inert gas to block the smoke on the outer surface of the filter element, thereby preventing the smoke from affecting the quality of the workpiece. When a certain amount of smoke accumulates on the outer surface of the filter element in the first filter module, the filter element can be backblown and dusted by a backblowing cleaning device to remove the smoke adsorbed on the outer surface of the filter element. In this way, not only can the service life of the filter element be extended, but also the use cost and labor cost of frequent replacement of the filter element can be reduced, and the quality of the workpiece can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The system structure of this embodiment is shown in FIG. Figure 1 ;

[0024] Figure 2 The system structure of this embodiment is shown in FIG. Figure 2 ;

[0025] Figure 3 2 is a system architecture diagram of this embodiment.

[0026] The parts indicated by the numbers in the above figures are as follows: 1. Printer; 2. Forming chamber; 3. Air outlet; 4. Air outlet duct; 5. First filter module; 6. Recovery duct; 7. Air inlet; 8. Clean air chamber; 9. Dust air chamber; 10. Partition; 11. Vent; 12. Power source; 13. Filter element; 14. Back-blowing cleaning device; 15. Air inlet valve of air storage tank; 16. Back-blowing air storage tank; 17. Pulse valve; 18. Air source; 19. First ash storage bucket; 20. First on-off device; 21. Second on-off device Filter module; 22. Second on-off device; 23. Third on-off device; 24. Pre-filter device; 25. Post-filter device; 26. First differential pressure sensor; 27. Second differential pressure sensor; 28. High-pressure signal terminal; 29. ​​Low-pressure signal terminal; 30. Control module; 31. Air wash inlet valve; 32. Air wash outlet valve; 33. Anemometer; 34. Frequency converter; 35. Power fan; 36. Connecting port; 37. Fourth on-off device; 38. Second ash storage bin; 39. Closed shell; 40. High-efficiency filter element. DETAILED DESCRIPTION

[0027] The utility model is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0028] like Figure 1 , Figure 2 and Figure 3 As shown, a parallel dual-filter dust removal system for SLM equipment disclosed in this embodiment includes a printer 1, the printer 1 includes a molding chamber 2, the air outlet 3 of the molding chamber 2 is connected to a first filter module 5 through an air outlet pipe 4, the first filter module 5 is connected to an air inlet 7 of the molding chamber 2 through a recovery pipe 6, and the first filter module 5 includes a clean air chamber 8 and a dust air chamber 9 arranged up and down, the clean air chamber 8 is connected to the recovery pipe 6, and the dust air chamber 9 is connected to the air outlet pipe 4. A partition 10 is arranged between the clean air chamber 8 and the dust air chamber 9, and three vents 11 are penetrated on the partition 10. A power source 12 is arranged on the recovery pipe 6 to drive the gas in the molding chamber 2 to run along the air outlet pipe 4, the dust air chamber 9, the clean air chamber 8 and the recovery pipe 6 in sequence. Specifically, the power source 12 includes a frequency converter 34 and a power fan 35 coupled to the frequency converter 34. A filter element 13 is disposed below the vent 11 , and a back-blowing and dust-removing device 14 is connected to the clean air chamber 8 for back-blowing the filter element 13 through the vent 11 to remove dust.

[0029] In this embodiment, the back-blowing cleaning device 14 includes an air tank inlet valve 15, a back-blowing air tank 16 and three pulse valves 17 connected in sequence. The other end of the air tank inlet valve 15 is connected to an air source 18, which can provide inert gas to the outside. The other end of the pulse valve 17 is connected to the top of the clean air chamber 8. The three pulse valves 17 and the three connecting ports 36 of the clean air chamber 8 are aligned with the three vents 11 one by one.

[0030] In order to receive and collect the smoke and dust dropped when the filter element 13 is back-blown for dust removal, a first ash storage bucket 19 is provided at the bottom of the dust and gas chamber 9. A first on-off device 20 is connected between the first ash storage bucket 19 and the bottom of the dust and gas chamber 9. The first on-off device 20 is preferably a cut-off butterfly valve to realize the disassembly and cleaning of the first ash storage bucket 19.

[0031] In order to realize back-blowing dust removal of the filter element 13 without stopping the equipment, the inlet and outlet of the first filter module 5 are connected in parallel with the second filter module 21, and the structure of the second filter module 21 is consistent with that of the first filter module 5. The inlet and outlet of the first filter module 5 are both provided with a second on-off device 22, and the inlet and outlet of the second filter module 21 are both provided with a third on-off device 23, and the second on-off device 22 and the third on-off device 23 are preferably pneumatic butterfly valves.

[0032] In this embodiment, when the two second on-off devices 22 simultaneously turn on the inlet and outlet of the first filter module 5 and the two third on-off devices 23 simultaneously cut off the inlet and outlet of the second filter module 21, the first filter module 5 enters the operating state and the second filter module 21 enters the waiting state, so that the equipment can back-blow and remove dust from the second filter module 21 without stopping.

[0033] On the contrary, when the two second on-off devices 22 simultaneously cut off the inlet and outlet of the first filter module 5 and the two third on-off devices 23 simultaneously connect the inlet and outlet of the second filter module 21, the first filter module 5 enters a waiting state and the second filter module 21 enters an operating state, so that the equipment can back-blow and remove dust on the first filter module 5 without stopping.

[0034] In order to reduce the loss of the first filter module 5 and the second filter module 21 and improve the dust removal performance of the entire dust removal system, a pre-filter device 24 is provided on the outlet pipe 4, and a post-filter device 25 is provided on the recovery pipe 6. The pre-filter device 24 is preferably a cyclone separator, and the bottom thereof is connected to the second ash storage bucket 38 through the fourth on-off device 37. The fourth on-off device 37 is also preferably a cut-off butterfly valve to achieve the disassembly and cleaning of the second ash storage bucket 38. The post-filter device 25 includes a closed shell 39 connected to the recovery pipe 6 and a high-efficiency filter element 40 arranged in the closed shell 39, so as to achieve higher precision smoke and dust interception.

[0035] In order to realize automatic switching and dust removal of the filter modules, the first filter module 5 and the second filter module 21 are respectively provided with a first differential pressure sensor 26 and a second differential pressure sensor 27. The high pressure signal end 28 and the low pressure signal end 29 of the first differential pressure sensor 26 are respectively provided in the dust and gas chamber 9 and the clean air chamber 8 of the first filter module 5 to detect the front and rear pressure difference of the filter element 13 in the first filter module 5. The high pressure signal end 28 and the low pressure signal end 29 of the second differential pressure sensor 27 are respectively provided in the dust and gas chamber 9 and the clean air chamber 8 of the second filter module 21 to detect the front and rear pressure difference of the filter element 13 in the second filter module 21. The first differential pressure sensor 26 and the second differential pressure sensor 27 are jointly coupled with a control module 30. The control module 30 is preferably a single chip microcomputer or a PLC. The air tank inlet valve 15, the pulse valve 17, the second on-off device 22 and the third on-off device 23 are all coupled and controlled by the control module 30. A pressure difference threshold is preset in the control module 30.

[0036] In this embodiment, when the first filter module 5 is running, if the pressure difference value measured by the first pressure difference sensor 26 is greater than or equal to the pressure difference threshold, it means that the loss of the filter element 13 in the first filter module 5 has reached a critical point. At this time, the control module 30 first controls the third on-off device 23 to be turned on, and then controls the second on-off device 22 to be turned off, so that the second filter module 21 enters the running state and the first filter module 5 enters the waiting state. Next, the control module 30 controls the air tank inlet valve 15 on the first filter module 5 to open, and after the pressure of the back-blowing air tank 16 is stabilized, the control module 30 controls the corresponding pulse valve 17 to start, so as to back-blow and remove dust from the filter element 13 in the first filter module 5.

[0037] On the contrary, when the second filter module 21 is running, if the pressure difference value measured by the second pressure difference sensor 27 is greater than or equal to the pressure difference threshold, it means that the loss of the filter element 13 in the second filter module 21 has reached the critical point. At this time, the control module 30 first controls the second on-off device 22 to be turned on, and then controls the third on-off device 23 to be turned off, so that the first filter module 5 enters the running state and the second filter module 21 enters the waiting state. Next, the control module 30 controls the air tank inlet valve 15 on the second filter module 21 to open, and after the pressure of the back-blowing air tank 16 is stabilized, the control module 30 controls the corresponding pulse valve 17 to start, so as to back-blow and remove dust from the filter element 13 in the second filter module 21.

[0038] In order to reduce the oxygen content in the idle filter module, the inlet and outlet of the first filter module 5 are respectively provided with a scrubbing inlet valve 31 and a scrubbing outlet valve 32 coupled and controlled by the control module 30, and the inlet and outlet of the second filter module 21 are also respectively provided with a scrubbing inlet valve 31 and a scrubbing outlet valve 32 coupled and controlled by the control module 30, and both scrubbing inlet valves 31 are connected to the gas source 18. Before the first filter module 5 or the second filter module 21 switches from the waiting state to the running state, the control module 30 controls the corresponding scrubbing inlet valve 31 and the scrubbing outlet valve 32 to open, so as to scrub the first filter module 5 or the second filter module 21 in the waiting state through the gas source 18. After scrubbing is completed, the control module 30 controls the corresponding scrubbing inlet valve 31 and the scrubbing outlet valve 32 to close, so as to seal the first filter module 5 or the second filter module 21 in the waiting state.

[0039] In order to keep the wind field in the dust removal system stable, an anemometer 33 is provided on the recovery pipe 6, and a control module 30 is coupled to the anemometer 33. The frequency converter 34 in the power source 12 is coupled to and controlled by the control module 30. The anemometer 33 is used to measure the wind speed value in the recovery pipe 6 and feed the measured wind speed value back to the control module 30 in real time. A wind speed threshold is preset in the control module 30.

[0040] When the printer 1 is in the powder spreading stage, the control module 30 can adjust the output frequency of the frequency converter 34 according to the difference between the wind speed value fed back by the anemometer 33 and the wind speed threshold, so as to adjust the power of the power fan 35, thereby changing the output power of the power source 12, and further maintaining the wind speed in the recovery pipe 6 at the wind speed threshold.

[0041] When the printer 1 is in the laser scanning stage, the control module 30 controls the output frequency of the frequency converter 34 to maintain the output power of the power source 12 at the state before entering the laser scanning, so that the wind speed in the recovery pipe 6 is maintained at the wind speed threshold. In this way, the stability of the wind field in the dust removal system can be effectively maintained.

[0042] The above control process can be implemented with the help of a built-in program or an equivalent analog circuit of the control module 30, which is common knowledge in the art and will not be elaborated here.

Claims

1. A parallel dual-filter dust removal system for SLM equipment, comprising a printer (1), the printer (1) comprising a molding chamber (2), characterized in that: The air outlet (3) of the molding chamber (2) is connected to a first filter module (5) via an air outlet pipe (4); the first filter module (5) is connected to an air inlet (7) of the molding chamber (2) via a recovery pipe (6); the first filter module (5) comprises a clean air chamber (8) and a dust air chamber (9) arranged above and below; the clean air chamber (8) is connected to the recovery pipe (6), and the dust air chamber (9) is connected to the air outlet pipe (4); a partition plate (10) is arranged between the clean air chamber (8) and the dust air chamber (9); 0), at least one vent (11) is passed through the partition (10), and a power source (12) is provided on the recovery pipe (6) to drive the gas in the molding chamber (2) to flow along the outlet pipe (4), the dust chamber (9), the clean air chamber (8) and the recovery pipe (6) in sequence; a filter element (13) is provided below the vent (11), and a back-blowing and dust-removing device (14) is connected to the clean air chamber (8) for back-blowing the filter element (13) through the vent (11) to remove dust.

2. A parallel dual filter element dust removal system for SLM equipment according to claim 1, characterized in that: The back-blowing cleaning device (14) comprises an air tank inlet valve (15), a back-blowing air tank (16) and a pulse valve (17) which are connected in sequence. The other end of the air tank inlet valve (15) is connected to an air source (18). The other end of the pulse valve (17) is connected to the top of the clean air chamber (8). The number of the pulse valves (17) is consistent with the number of the filter element (13), and the connection ports (36) of the pulse valves (17) and the clean air chamber (8) are aligned with one or more vents (11).

3. A parallel dual filter element dust removal system for SLM equipment according to claim 1 or 2, characterized in that: A first ash storage bucket (19) is arranged at the bottom of the dust and gas chamber (9).

4. A parallel dual filter element dust removal system for SLM equipment according to claim 3, characterized in that: A first on-off device (20) is connected between the first ash storage bucket (19) and the bottom of the dust and gas chamber (9).

5. A parallel dual filter element dust removal system for SLM equipment according to claim 2, characterized in that: The inlet and outlet of the first filter module (5) are connected in parallel with a second filter module (21), the structure of the second filter module (21) is consistent with that of the first filter module (5), the inlet and outlet of the first filter module (5) are both provided with a second on-off device (22), and the inlet and outlet of the second filter module (21) are both provided with a third on-off device (23); When the two second on-off devices (22) simultaneously connect the inlet and outlet of the first filter module (5) and the two third on-off devices (23) simultaneously cut off the inlet and outlet of the second filter module (21), the first filter module (5) enters an operating state and the second filter module (21) enters a waiting state; conversely, when the two second on-off devices (22) simultaneously cut off the inlet and outlet of the first filter module (5) and the two third on-off devices (23) simultaneously connect the inlet and outlet of the second filter module (21), the first filter module (5) enters a waiting state and the second filter module (21) enters an operating state.

6. A parallel dual filter element dust removal system for SLM equipment according to claim 1 or 2, characterized in that: A pre-filter device (24) is provided on the air outlet pipe (4).

7. A parallel dual filter element dust removal system for SLM equipment according to claim 1 or 2, characterized in that: A post-filtering device (25) is provided on the recovery pipeline (6).

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