Continuous drying device for metal powder for 3D printing

Abstract

The utility model relates to the technical field of metal powder drying devices, in particular to a continuous drying device of metal powder for 3D printing, which comprises a powder storage tank, a drying tank, a cyclone separation tank, a dehumidification tank, a high-pressure fan, a heating tank and a conveying pipeline, and the lower end of the cyclone separation tank is provided with a powder outlet; the powder storage tank is communicated with the upper end of the drying tank, other facilities are sequentially and circularly communicated through a conveying pipeline, the conveying pipeline is communicated with an inert gas inlet, and a one-way gas release valve is further arranged in the continuous drying device so as to ensure that the whole drying process is protected by inert gas; an inclined plate is installed in the drying tank, metal powder slides off along the inclined plate in a zigzag mode and makes full contact with heated inert gas in the process, and the dried powder is driven by airflow to enter the cyclone separation tank, spontaneously deposits due to gravity and flows out from a powder outlet. According to the scheme, a large amount of metal powder of various specifications and shapes can be continuously dried, and good safety and universality are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of metal powder drying devices, and in particular to a continuous drying device for metal powder for 3D printing. Background Art

[0002] Selective laser sintering (SLS) and selective laser melting (SLM) are the mainstream production technologies in metal 3D printing. The metal powder used for printing will inevitably become damp due to the absorption of water during transportation and storage, which will seriously affect the fluidity of the metal powder. If the damp metal powder is directly put into production, uneven powder spreading, powder agglomeration and oxidation are likely to occur during the printing production process. At this time, the dimensional accuracy and surface quality of the printed parts will decrease, and pore defects, unmelted defects and oxidation defects will occur inside the parts, seriously affecting the density and mechanical properties of the parts.

[0003] Therefore, in order to ensure the quality of 3D printed products, the metal powder needs to be dried before printing. The current drying method is usually to place the metal powder in a tray, and then put multiple sets of trays into a vacuum drying oven for 1 to 4 hours. After the metal powder cools down with the furnace, the drying is completed, and the dry metal powder can be manually transferred to a powder storage tank or other equipment. However, this method has certain disadvantages. First, it is inefficient. The entire heating process needs to go through three steps of "heating-insulation-cooling", which is time-consuming, and the weight of the powder that can be dried is seriously dependent on the number and size of the drying equipment. Secondly, the drying effect of the upper and lower layers of metal powder in the tray is inconsistent; moreover, this method is more troublesome. In order to ensure the drying effect, the metal powder needs to be turned over many times during drying, which increases the risk of oxidation contamination of the powder. Utility Model Content

[0004] In order to solve the problems in the prior art that metal powder has low drying efficiency and is easily oxidized during the turnover process, the present application provides a continuous drying device for metal powder for 3D printing.

[0005] The present application provides a continuous drying device for metal powder for 3D printing, which adopts the following technical solution:

[0006] A continuous drying device for metal powder for 3D printing, comprising a powder storage tank, a drying tank, a cyclone separation tank, a dehumidification tank, a high-pressure fan, a heating tank and a conveying pipeline, wherein the powder storage tank is connected to the upper end of the drying tank, and the lower end of the cyclone separation tank is provided with a powder outlet;

[0007] The conveying pipeline includes a first pipeline connecting the drying tank and the cyclone separation tank, a second pipeline connecting the cyclone separation tank and the dehumidification tank, a third pipeline connecting the dehumidification tank and the high-pressure fan, a fourth pipeline connecting the high-pressure fan and the heating tank, and a fifth pipeline connecting the heating tank and the drying tank;

[0008] The drying tank is connected to a pressure detection gauge, a temperature detection gauge and an oxygen content detection gauge, the fourth pipeline is provided with an inert gas inlet, and a one-way air release valve is provided on one side of the dehumidification tank; a drying chamber is provided in the drying tank, and an inclined plate is provided on the inner wall of the drying chamber, the inclined plate is inclined downward, and the inclined plate is used to extend the falling distance of the metal powder, and a discharge port is provided at the lower end of the drying tank, and the discharge port is connected to the first pipeline.

[0009] Optionally, the inclined plates are a plurality of cross-distributed planar plates.

[0010] Optionally, the inclined plate is a curved plate that spirals continuously downward.

[0011] Optionally, the third pipeline is provided with a humidity monitoring meter.

[0012] Optionally, a heating resistance wire and an insulating flame-retardant filler are provided inside the heating tank, and the insulating flame-retardant filler is wrapped around the outer periphery of the heating resistance wire.

[0013] Optionally, the conveying pipeline is an anti-static corrugated hose, and the high-pressure fan and the heating tank are both grounded.

[0014] Optionally, all interfaces are sanitary quick-release interfaces.

[0015] In summary, the present application includes at least one of the following beneficial technical effects:

[0016] 1. Compared with the existing 3D printing metal powder drying technology that uses a tray with a large drying box, this technical solution has the characteristics of small equipment footprint, high drying efficiency, and low energy consumption. It can achieve automation to a great extent and reduce the workload of operators.

[0017] 2. In this solution, the entire process of drying the metal powder is carried out under the protection of inert gas, which effectively reduces the risk of oxidation, contamination and spontaneous combustion of the metal powder due to the transfer between the powder storage tank and the tray in the prior art. The conveying pipeline is circularly connected and a dehumidification tank is provided, so that the inert gas can be recycled after dehumidification, which has good safety, environmental protection and economy.

[0018] 3. The drying device is suitable for metal powders of various specifications and shapes. During the drying operation, there is no need to consider factors such as the particle size, quantity, and chemical activity of the metal powder to be processed. It has good versatility and can realize continuous drying of large amounts of powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the continuous drying device for metal powder for 3D printing of the present application.

[0020] Explanation of the reference numerals: 1. powder storage tank; 11. charging port; 2. drying tank; 21. feeding port; 22. discharging port; 23. drying chamber; 24. hot air inlet; 25. pressure detection gauge; 26. temperature detection gauge; 27. oxygen content detection gauge; 28. inclined plate; 3. cyclone separation tank; 31. powder outlet; 4. dehumidification tank; 41. one-way air release valve; 42. desiccant; 5. high-pressure fan; 6. heating tank; 61. heating resistor wire; 62. insulating flame-retardant filler; 7. conveying pipeline; 71. first pipeline; 72. second pipeline; 73. third pipeline; 731. humidity monitoring gauge; 74. fourth pipeline; 741. inert gas inlet; 75. fifth pipeline. DETAILED DESCRIPTION

[0021] The following is combined with Figure 1 This application is described in further detail.

[0022] The present application embodiment discloses a structural schematic diagram of a continuous drying device for metal powder for 3D printing. Figure 1 The continuous drying device for metal powder for 3D printing includes a powder storage tank 1, a drying tank 2, a cyclone separation tank 3, a dehumidification tank 4, a high-pressure fan 5, a heating tank 6 and a conveying pipeline 7.

[0023] The drying tank 2, the cyclone separation tank 3, the dehumidification tank 4, the high-pressure fan 5, and the heating tank 6 are circulated and connected in sequence through the conveying pipeline 7. The conveying pipeline 7 includes a first pipeline 71 connecting the drying tank 2 and the cyclone separation tank 3, a second pipeline 72 connecting the cyclone separation tank 3 and the dehumidification tank 4, a third pipeline 73 connecting the dehumidification tank 4 and the high-pressure fan 5, a fourth pipeline 74 connecting the high-pressure fan 5 and the heating tank 6, and a fifth pipeline 75 connecting the heating tank 6 and the drying tank 2. All interfaces are sanitary quick-install interfaces, and valves that can be closed are set according to actual needs. The valves can be gate valves, stop valves, ball valves or butterfly valves. In order to ensure safety, the conveying pipeline 7 is an anti-static corrugated hose, and the high-pressure fan 5 and the heating tank 6 are grounded.

[0024] The fourth pipe 74 is connected to the inert gas inlet 741, and a one-way air release valve 41 is installed on one side of the dehumidification tank 4. The embodiment of the present application takes the input of argon gas into the inert gas inlet 741 as an example, and the entire pneumatic transport process is protected by argon gas, which can prevent the active metal powder from being contaminated.

[0025] The upper end of the powder storage tank 1 is provided with a loading port 11, the upper end of the drying tank 2 is provided with a feeding port 21, the lower end of the powder storage tank 1 is connected to the feeding port 21 through a quick-fit interface, and a valve is installed at the quick-fit interface, and the valve is used to control the speed at which the metal powder falls from the powder storage tank 1 into the drying tank 2. The lower end of the drying tank 2 is provided with a discharge port 22, and the discharge port 22 is connected to the cyclone separation tank 3 through a first pipe 71.

[0026] A drying chamber 23 is formed inside the drying tank 2, and the drying chamber 23 is connected to the feed port 21 and the discharge port 22. A hot air inlet 24 is provided at the upper end of the drying tank 2 near the feed port 21, and the hot air inlet 24 is connected to the heating tank 6 through the fifth pipe 75. A pressure detection gauge 25, a temperature detection gauge 26 and an oxygen content detection gauge 27 are installed on the side wall of the drying tank 2, and the three jointly monitor the drying conditions in the tank. There is a linkage control relationship between the output power of the heating tank 6 and the temperature detection gauge 26, so that the drying temperature can be controlled. The specific linkage control relationship is a prior art and will not be repeated. The linkage control relationship between the inert gas inlet 741 valve and the pressure detection gauge 25, and the linkage control relationship between the inert gas inlet 741 valve and the oxygen content detection gauge 27 are also prior art and will not be repeated.

[0027] An inclined plate 28 is welded to the inner wall of the drying chamber 23. The inclined plate 28 is arranged to be inclined downward, and is used to disperse the metal powder falling from the feed port 21 to increase the contact area between the metal powder and the heated gas, and to extend the falling distance of the metal powder, thereby extending the contact time between the two, and achieving the effect of drying the metal powder. In one specific embodiment, the inclined plate 28 is a plurality of cross-distributed flat plates; in another specific embodiment, the inclined plate 28 is a curved plate that spirals downward continuously. This application takes the first specific embodiment as an example.

[0028] The lower end of the cyclone separation tank 3 is provided with a powder outlet 31, which is used to connect to a target device such as a 3D printer or a powder transfer tank. After the metal powder is dried in the drying chamber 23, the dry metal powder enters the cyclone separation tank 3 with the airflow, and is separated from the flowing gas under the action of gravity. The deposited metal powder flows into the target device through the powder outlet 31, and the flowing gas continues to circulate in the system after being dehumidified by the dehumidification tank 4.

[0029] The dehumidification tank 4 is filled with a desiccant 42 , and the third pipe 73 is installed with a humidity monitoring meter 731 . The staff can judge whether the desiccant 42 needs to be replaced by a new one by observing the humidity monitoring meter 731 .

[0030] A heating resistor 61 is provided in the heating tank 6 to heat the airflow to a target temperature. In order to prevent short circuit and electric sparks, an insulating flame retardant filler 62 is also provided in the heating tank 6, and the insulating flame retardant filler 62 is wrapped around the outer periphery of the heating resistor 61.

[0031] The implementation principle of the continuous drying device for 3D printing metal powder in the embodiment of the present application is as follows: first close the valve at the feed port 21 and the valve at the powder outlet 31, open the valve at the inert gas inlet 741, introduce argon gas, judge the progress of the gas washing by the oxygen content detection meter 27, and wash until the oxygen content in the device is reduced to less than 300ppm, and then the gas washing is completed. During the gas washing process, the air in the system is discharged through the one-way air release valve 41.

[0032] The metal powder to be dried is added into the powder storage tank 1 from the loading port 11. After the loading is completed, the loading port 11 is closed and the system power is started to generate a pressure difference in the system, and the heating gas flows stably in the system. Subsequently, the valve of the powder outlet 31 and the valve of the feed port 21 are opened in sequence, and the opening size of the valve of the feed port 21 is adjusted according to the actual situation on site, so that the metal powder to be dried falls into the drying tank 2 at a suitable flow rate, specifically, it can ensure that the metal powder can pass through the discharge port 22 unimpeded and flow into the cyclone separation tank 3 without accumulating in the discharge port 22 or the first pipeline 71.

[0033] The dried metal powder is separated from the flowing gas under the action of gravity, and the metal powder flows into the target device through the powder outlet 31. The flowing gas enters the dehumidification tank 4 through the second pipe 72, and the water vapor is adsorbed by the desiccant 42. The dry gas enters the heating tank 6 driven by the high-pressure fan 5, and after being heated by the heating tank 6, it enters the drying tank 2 again along the fifth pipe 75, and continues the drying operation until all the metal powder in the powder storage tank 1 is dried. The valve of the powder outlet 31 and the valve of the feed port 21 are closed in turn, and then the system power is turned off. At this time, the system remains closed and protected by argon gas, so that the amount of gas washing can be reduced when used next time, and the gas washing step can even be omitted.

[0034] If the target device is a powder transfer tank, when the powder transfer tank is full, there is no need to turn off the system power supply. The valve of the powder outlet 31 can be temporarily closed, and the empty powder transfer tank can be replaced in time, and then the valve of the powder outlet 31 can be opened to achieve continuous drying operation. If the operation steps of filling the powder storage tank 1 with powder and discharging the powder from the cyclone separation tank 3 are completed by automatic transfer equipment, the full automation of the large-scale 3D printing metal powder drying operation can be achieved. If the metal powder is seriously affected by moisture, the metal powder transferred from the cyclone separation tank 3 can be filled back into the powder storage tank 1 again, and the drying can be repeated multiple times.

[0035] In order to avoid insufficient gas pressure in the system due to argon leakage, when the system is started, the inert gas inlet 741 will replenish the system in real time according to the feedback values ​​of the pressure detection meter 25 and the oxygen content detection meter 27.

[0036] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A continuous drying device for metal powder for 3D printing, characterized in that: The invention comprises a powder storage tank (1), a drying tank (2), a cyclone separation tank (3), a dehumidification tank (4), a high-pressure fan (5), a heating tank (6) and a conveying pipeline (7), wherein the powder storage tank (1) is connected to the upper end of the drying tank (2), and the lower end of the cyclone separation tank (3) is provided with a powder outlet (31); The conveying pipeline (7) comprises a first pipeline (71) connecting the drying tank (2) and the cyclone separation tank (3), a second pipeline (72) connecting the cyclone separation tank (3) and the dehumidification tank (4), a third pipeline (73) connecting the dehumidification tank (4) and the high-pressure fan (5), a fourth pipeline (74) connecting the high-pressure fan (5) and the heating tank (6), and a fifth pipeline (75) connecting the heating tank (6) and the drying tank (2); The drying tank (2) is connected to a pressure detection gauge (25), a temperature detection gauge (26) and an oxygen content detection gauge (27); the fourth pipeline (74) is provided with an inert gas inlet (741), and a one-way air release valve (41) is provided on one side of the dehumidification tank (4); a drying chamber (23) is provided in the drying tank (2); an inclined plate (28) is provided on the inner wall of the drying chamber (23); the inclined plate (28) is arranged to be inclined downward, and the inclined plate (28) is used to extend the falling distance of the metal powder; a discharge port (22) is provided at the lower end of the drying tank (2); the discharge port (22) is communicated with the first pipeline (71).

2. A continuous drying device for metal powder for 3D printing according to claim 1, characterized in that: The inclined plates (28) are a plurality of cross-distributed planar plates.

3. The continuous drying device for metal powder for 3D printing according to claim 1, characterized in that: The inclined plate (28) is a curved plate that spirals downward continuously.

4. The continuous drying device for metal powder for 3D printing according to claim 1, characterized in that: The third pipeline (73) is provided with a humidity monitoring meter (731).

5. The continuous drying device for metal powder for 3D printing according to claim 4, characterized in that: A heating resistance wire (61) and an insulating flame-retardant filler (62) are provided inside the heating tank (6), and the insulating flame-retardant filler (62) is wrapped around the outer periphery of the heating resistance wire (61).

6. The continuous drying device for metal powder for 3D printing according to claim 4, characterized in that: The delivery pipeline (7) is an anti-static corrugated hose, and the high-pressure fan (5) and the heating tank (6) are both grounded.

7. The continuous drying device for metal powder for 3D printing according to claim 4, characterized in that: All interfaces are sanitary quick-install interfaces.

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