3D printing powder recycling method

Abstract

The invention discloses a 3D printing powder recycling method which is characterized in that after printing is completed, unformed powder in a forming cylinder is conveyed into a closed treatment container in a suction mode, then part of unprinted powder new materials are added after crushing and screening treatment, and the powder is recycled. And uniformly mixing, drying, and discharging for repeated printing. According to the 3D printing powder recycling device, powder recycling can be better achieved, the powder loss is small, the powder recycling quality is high, the 3D printing powder recycling device has the advantages of being convenient to operate, sanitary and tidy in site environment and the like, and the overall 3D printing cost is better saved.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D powder printing, and in particular to a method for recycling 3D printed powder. Background Art

[0002] Additive manufacturing, also known as 3D printing, works by stacking materials layer by layer to form an object. This technology has two significant characteristics: on the one hand, it can manufacture components with extremely complex shapes to meet various special design requirements; on the other hand, it has extremely high forming accuracy, which can ensure the quality and performance of products. In practical applications, 3D printing technology has prominent advantages. It can not only effectively save materials, reduce production costs, but also support personalized customization to meet diverse market demands. At the same time, it simplifies the production process, improves production efficiency, and realizes energy conservation and environmental protection during the production process, in line with the concept of green development. Based on these advantages, 3D printing technology has been widely applied in many fields such as aerospace, medical, military, and construction, bringing new changes and opportunities to the development of various industries.

[0003] After years of development, various 3D printing technologies have been developed, with different functions. Currently, 3D printing technologies include binder jetting, directed energy deposition, material extrusion, material jetting, powder bed fusion, sheet lamination, and vat photopolymerization, etc. However, most of these types of 3D printing require the use of powder as the base material and layer-by-layer powder spreading before printing and forming. Although only the powder within the printed shape range of the component is cured during each layer of powder printing, the remaining powder may also be scrapped due to the action of the splashed printing curing material and cannot be directly reused. This leads to a large waste of powder materials, making the printing cost too high. Especially for metal powder printing technology, the powder itself has a high cost. Currently, the promotion and application of metal 3D printing technology face significant obstacles, and the high cost due to the expensive metal powder is the core factor of this problem.

[0004] To reduce costs, it is necessary to recycle the residual powder after forming. The conventional recycling method is to collect the remaining powder in the printing cylinder after the printed component is taken away, and then through separate treatment processes such as screening and drying to achieve recycling. This has defects such as large losses, rapid decline in powder quality, and long time consumption. At the same time, during the powder transfer process, there is a large amount of dust, which affects the working environment and the health of operators.

[0005] Therefore, how to design a powder recycling utilization scheme with less powder loss, higher powder recycling quality, which can better realize powder recycling utilization and a more hygienic and clean environment has become a technical problem that needs to be considered and solved by those skilled in the art. Summary of the Invention

[0006] Aiming at the deficiencies of the above-mentioned existing technologies, the technical problem to be solved by the present invention is: how to provide a 3D printing powder recycling method that can better realize powder recycling with less powder loss and higher powder recycling quality, and further make it have the characteristics of convenient operation, clean on-site environmental hygiene, etc., and better save the overall cost of 3D printing.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions: A 3D printing powder recycling method, characterized in that after printing is completed, the unformed powder in the forming cylinder is sent to a closed treatment container by suction, then after crushing and screening treatment, a part of the unprinted powder new material is added, and then mixed evenly and dried before discharging for repeated printing use.

[0008] In this way, in this method, the unformed powder after printing is first sucked away by suction. After the powder is sucked away, the printed component can be discharged, making it more convenient to take out the component. The sucked powder is crushed and screened, and part of the powder that has caked due to contamination with a small amount of printing curing material can be broken and recycled. By relying on screening to ensure the powder particle size requirements, the powder loss is greatly reduced. Then a certain proportion of powder new material is added for mixing, ensuring a higher powder recycling quality and better ensuring the product forming quality. Finally, the evenly mixed powder is dried to remove the absorbed excess moisture and can be used for secondary printing. Therefore, there are the characteristics of less powder loss and higher powder recycling quality.

[0009] Furthermore, the added mass ratio range of the powder new material is 30%-50%. Using the new material within this range ratio can ensure that the printed powder has sufficient recycling value and ensure that the mixed powder has sufficient printing quality.

[0010] Furthermore, the suction process is realized by a 3D printing powder suction device. The 3D printing powder suction device includes a housing with a closed container structure. An air pipe is connected and communicated outward at the upper end of the housing. A powder outlet is arranged downward at the lower end of the housing. A powder outlet switch is arranged at the powder outlet. An air flow outlet is also arranged on one side of the housing and is connected and communicated outward with an air flow channel. A filter screen with a mesh smaller than the powder particle size is arranged at the air flow outlet. A fan is arranged in the air flow channel.

[0011] In this way, when the 3D printing powder suction device works, first keep the powder outlet switch closed, and then start the fan to generate suction at the air pipe, so that the powder in the forming cylinder of the printing device can be quickly sucked into the inner cavity of the housing. The air flow is discharged through the air flow channel, and the powder is retained in the device. When subsequent process operations are required, open the powder outlet switch to let the powder leak out.

[0012] Further, the straw is a corrugated pipe. In this way, the straw has flexibility and can better complete the suction of powder materials.

[0013] Further, the overall structure of the outer shell and the inner cavity is a rectangular body structure, and the powder outlet at the lower end is a matching rectangle.

[0014] In this way, the shape of the powder outlet of the powder suction device matches the shape of the screening basket in the subsequent crushing and screening device, making the powder fall from the powder outlet of the powder suction device into the screening basket more evenly, which is convenient for the subsequent realization of crushing and screening.

[0015] Further, the powder outlet switch includes a powder baffle horizontally arranged at the powder outlet. The powder baffle is slidably installed on the insertion interface on the inner wall of the powder outlet and has an insertion handle end exposed from the insertion interface.

[0016] In this way, the powder can be made to fall neatly and evenly from the powder outlet into the screening basket of the crushing and screening device by means of insertion and extraction, which is convenient for the subsequent realization of crushing and screening.

[0017] Further, the crushing and screening process is realized by a 3D printing powder crushing and screening device. The 3D printing powder crushing and screening device includes a screening box. A screening box inlet for powder to enter is arranged at the upper end of the screening box, and a screening box outlet for powder to discharge is arranged at the lower end. A crushing mechanism and a screening mechanism are arranged in the inner cavity of the screening box. The screening mechanism includes a horizontally arranged screening basket. The screening basket is located in the upper part of the inner cavity of the screening box and is below the screening box inlet. The four corner positions of the screening basket are fixed on the upper end wall of the inner cavity of the screening box by vertically upward spiral springs. The screening device is connected to a vibrator, and the lower surface of the screening basket is a horizontally fixed screen mesh.

[0018] In this way, the powder falls from the screening box inlet into the screening box and then onto the screening basket. After being crushed by the crushing mechanism, the screening is realized by driving the screening basket by the vibrator. During screening, the screening basket generates vibration driven by the vibrator and the vibration effect is amplified by the four spiral springs at the corners, improving the screening efficiency. In this way, through screening, it is ensured that the particle size of the falling powder can meet the regeneration requirements, realizing the efficient regeneration screening treatment of 3D printing powder.

[0019] Furthermore, the screening basket is rectangular as a whole, and the crushing mechanism includes a crushing roller arranged in the screening basket along the width direction, and ear plates along the length direction are upwardly arranged on the side edges of the screening basket in the width direction, and horizontal guide rail grooves are opened on the ear plates along the length direction. The circumferential surface of the crushing roller is provided with crushing protrusions of equal height in rows along the axial direction, and each row of crushing protrusions is evenly distributed in the circumferential direction. The roller shafts at both ends of the crushing roller are also respectively sleeved with an elastic roller sleeve, which fits in the guide rail groove. The outer end of the roller shaft is rotatably mounted vertically on a connecting rod arranged obliquely downward through a bearing, and the lower end of the connecting rod is rotatably connected to the outer end of a crank to form a crank-connecting rod mechanism, the crank is connected to a crushing and screening motor located below one end of the screening basket, and the crank-connecting rod mechanism applies a downward pre-tension to the screening basket.

[0020] In this way, the crushing and screening motor drives the roller shaft to roll horizontally in the guide groove through the crank connecting rod mechanism. Since the crank connecting rod mechanism applies a downward pre-tension to the screening basket, the pre-tension is offset by the action of four spiral springs to keep the screening basket balanced. In this way, since the roller shaft is matched with the guide groove through the elastic roller sleeve with elasticity, the height of the crushing protrusion on the crushing roller matches the elastic deformation size of the elastic roller sleeve. When the crushing roller rotates until the crushing protrusion is facing downward and in contact with the screen surface, the elastic roller sleeve is in a state of no stress in the middle position (at this time, the pre-tension of the crank connecting rod directly acts on the screen and the screening basket downward through the crushing roller and the crushing protrusion). When the crushing roller continues to rotate, the crushing protrusion rotates forward and disengages from the contact with the screen surface. The screen and the screening basket reset upward under the action of the spiral spring, and the elastic roller sleeve switches to an extrusion stress deformation state (at this time, the pre-tension of the crank connecting rod acts on the screening basket through the elastic roller sleeve). In this way, the crushing roller switches between two states repeatedly when rolling, driving the screen to vibrate up and down. At the same time, since the crushing roller itself is rolling forward when switching between the two states, the friction force component generated by its rolling will cause a component force in the horizontal direction and produce a horizontal swing. Therefore, the rolling of the crushing roller itself in the above-mentioned device can produce a crushing effect on the powder. At the same time, the coordinated movement effect produced by the mutual cooperation between the various structures makes the crushing roller form a vibrator while rolling, and drives the screen to produce a composite vibration effect of up and down vibration and front and back swing superimposed, greatly improving the screening efficiency and screening effect. The setting of the elastic roller sleeve allows the above-mentioned composite vibration effect to be better realized, while also ensuring the stability of the rolling process of the crushing roller itself during the composite vibration process of the screening basket driven by the crushing roller, and avoiding the influence of the reverse transmission of vibration to the motor to the greatest extent, thereby extending the life of the motor. Therefore, the crushed powder can be better vibrated and screened while ensuring the smooth and durable operation of the device.

[0021] Furthermore, the screening box is in a rectangular structure as a whole.

[0022] Further, the crushing and screening motor is installed on a motor bracket located below one end of the screening basket, which facilitates the installation and setup of the motor.

[0023] Further, the inlet of the screening box includes a first screening box inlet for sealing and docking with the powder outlet of a 3D printing powder suction device.

[0024] After the 3D printing powder suction device finishes sucking the powder, the powder can be directly input into the screening box through the first screening box inlet, avoiding powder spillage and affecting the environmental hygiene.

[0025] Further, the inlet of the screening box further includes a second screening box inlet, and a second screening box inlet switch cover is provided at the upper end of the second screening box inlet.

[0026] This is because 3D printing devices usually have devices for collecting overflow powder, such as an overflow powder tank. The amount of powder in this part is relatively small and it is not convenient to directly suck it with a straw. Therefore, the second screening box inlet switch cover can be directly opened to pour this part of the powder into the screening box for screening treatment.

[0027] Further, a conical discharge hopper is provided downward at the lower end of the screening box, and a screening box outlet is formed below the discharge hopper, which is more convenient for the screening box to discharge materials.

[0028] Further, the step of adding, mixing and drying new powder materials is realized by a 3D printing powder mixing device. The 3D printing powder mixing device includes a vertically cylindrical shell. At the upper end of the shell, a recycled powder interface and a new powder adding interface are respectively opened upward. A sprinkling and mixing device is further provided in the upper part of the inner cavity of the shell, and a jolting and mixing device and a discharging device are provided in the lower part of the shell.

[0029] In this way, the recycled powder enters from the recycled powder inlet, and the new powder enters from the new powder adding inlet. The two kinds of powders are mixed in the inner cavity of the shell through two different mixing methods of the sprinkling and mixing device and the jolting and mixing device in sequence, so that they are better mixed evenly and then discharged, which better improves the mixing efficiency and mixing quality.

[0030] Further, an electric heating module interlayer is also provided in the shell. In this way, by using electric heating to heat the powder inside, drying can be quickly achieved, avoiding the influence of moisture in the powder on subsequent use.

[0031] Further, a protective gas device is also installed on the shell. The protective gas device includes an air extraction joint and an air inlet joint exposed in the inner cavity wall of the shell. The air extraction joint is externally connected to an air extraction pipeline and is used to connect to an air extraction fan. The air inlet joint is externally connected to an air inlet pipeline and is used to connect to a protective gas cylinder. Control valves are also installed on the air extraction pipeline and the air inlet pipeline.

[0032] In this way, the control valve is connected to the control center. When some powder materials need to isolate air during the heating and drying process, the air extraction joint can be controlled to extract air from the inner cavity of the housing, and then the intake joint can be controlled to introduce a protective gas to isolate the internal air to form an atmosphere protection, avoiding oxidation and denaturation of the powder materials during heating. During implementation, an oxygen sensor probe can be further installed on the inner wall of the housing and connected to the control center to better achieve control.

[0033] Furthermore, a feed channel is respectively upwardly connected to the recycled powder interface and the newly added powder interface, and a feed control switch is arranged at the lower end position of the feed channel. This facilitates the control of the feed.

[0034] Furthermore, the feed control switch includes a feed switch baffle, which is horizontally arranged on the insertion opening on one side of the feed channel in a pullable manner. The outer end of the feed switch baffle can be inserted and pulled out of the insertion opening and is connected to an electric push rod device for feed control located at the upper end of the housing. A weighing sensor is also arranged on the feed switch baffle.

[0035] In this way, after the powder materials enter the feed channel, they can be weighed by the weighing sensor. After meeting the requirements, the electric push rod device is controlled to pull the feed switch baffle so that the powder materials fall into the inner cavity of the housing, facilitating the control of the feed ratio of the recycled powder and the newly added powder. During implementation, the output end of the weighing sensor is connected to the input end of the weight transmitter (or directly connected to the control center), and the output end of the weight transmitter is connected to the input end of the electric push rod. Parameters can be set for the weight transmitter, and the output signal of the weighing sensor will be compared with the set value in the weight transmitter. When the weight reaches the set weight, the weight transmitter will input a corresponding control signal to the electric push rod to make the electric push rod work.

[0036] Furthermore, a dust-proof cover is also arranged at the upper end of the housing. The upper end of the feed channel at the upper end of the recycled powder interface passes through the dust-proof cover and is used for docking with the outlet of the screening box of the 3D printing powder crushing and screening device. The upper end of the feed channel above the newly added powder interface passes through the dust-proof cover and is provided with an outwardly folded section, and a switch cover is arranged at the upper end of the folded section.

[0037] In this way, it is convenient to achieve dust-proof for the feed and ensure environmental hygiene.

[0038] Furthermore, the sprinkling and mixing device includes a sprinkling and mixing rotating shaft vertically installed in the middle of the upper end of the inner cavity of the housing. The upper end of the sprinkling and mixing rotating shaft rotatably passes through the housing and is connected to a sprinkling and mixing motor installed at the upper end of the housing. Several first mixing blades are evenly arranged along the circumference at the upper part of the sprinkling and mixing rotating shaft. The projections of the recycled powder interface and the newly added powder interface downward fall within the rotation range of the first mixing blades. A material dropping funnel is arranged outside the first mixing blades. The upper end of the material dropping funnel is fixed at the upper end of the inner cavity of the housing, and the lower end outlet is suspended. The lower end of the sprinkling and mixing rotating shaft extends downward beyond the lower end outlet of the material dropping funnel, and several second mixing blades are evenly installed along the circumference at the lower end of the sprinkling and mixing rotating shaft. The projection of the lower end outlet of the material dropping funnel downward falls within the rotation range of the second mixing blades.

[0039] In this way, when the device is in use, the sprinkling and mixing motor drives the first mixing blades and the second mixing blades to rotate at high speed. After the old and new powders enter the inner cavity of the housing from the recycled powder interface and the newly added powder interface respectively, they fall onto the first mixing blades, are scattered around by the first mixing blades rotating at high speed and mixed onto the material dropping funnel, converge downward through the material dropping funnel and then fall onto the second mixing blades again, and are scattered around by the second mixing blades rotating at high speed and fall into the lower part of the inner cavity of the housing. Compared with the conventional mixing method that is prone to mixing dead angles, in this device, during the dynamic process of the powder falling in the air, after being repeatedly scattered, mixed and dropped by the blades twice, an efficient and fast dynamic mixing process is achieved, and a good mixing effect is obtained. In addition, during the process of the sprinkling and mixing device relying on the rotating blades to scatter the powder, it can scatter the stringy powder particles that are difficult to remove by screening due to adhesion by the solidified material in one direction, break their adhesion, and better improve the regeneration quality of the powder, ensuring the forming effect during repeated use.

[0040] Furthermore, two rows of guiding protrusions are symmetrically arranged on the inner side surface of the material dropping funnel, with the upper ends of the guiding protrusions located at the middle positions on the left and right sides of the inner side surface of the material dropping funnel, and the lower ends extending spirally to the lower edge of the other side of the inner side surface of the material dropping funnel.

[0041] This is because when the old and new powders enter the inner cavity of the housing from the recycled powder interface and the newly added powder interface respectively and are scattered onto the material dropping funnel by the first mixing blades, there is still a large directionality, that is, the old and new powders will relatively concentrate and fall onto one side. Therefore, after setting the above guiding protrusions, a part (about half) of the powder scattered and dropped onto one side of the funnel can be guided by the guiding protrusions to fall onto the other side of the funnel. Then, after being scattered again by the second mixing blades, the mixing uniformity is greatly improved.

[0042] Furthermore, the guiding protrusions are arranged with the height gradually increasing from top to bottom. In this way, the above-mentioned powder guiding effect can be better ensured.

[0043] Furthermore, the tipping and mixing device includes a mixing basin located at the lower end of the inner cavity of the housing. The mixing basin has an upward opening and a circular shape that matches the inner cavity wall of the housing. The middle of the lower end of the mixing basin is supported and installed at the upper end of a vertically arranged tipping and mixing rotating shaft through a universal joint. The lower end of the tipping and mixing rotating shaft is connected to a tipping and mixing motor installed on the base. A vibration motor is also installed on the mixing basin. The vibration motor is used to output vertical vibration to the mixing basin. Multiple support rods are also downwardly provided at the peripheral position of the lower surface of the mixing basin. The support rods are evenly distributed in a ring centered on the tipping and mixing rotating shaft. The support rods have an upper half section and a lower half section that are inserted and matched with each other to form a sleeve structure. A vertical support spring is arranged inside the upper half section and the lower half section to form a vertical elastic support connection. The upper end of the upper half section is rotatably installed on the lower surface of the mixing basin through a hinge joint. The hinge axis direction of the hinge joint is arranged along the direction perpendicular to the diameter of the mixing basin. The lower end of the lower half section is rotatably supported and installed in a circular track groove on the upper surface of a base. At least one arc-shaped protrusion or depression is provided on the groove bottom surface of the track groove.

[0044] In this way, after the powder material falls into the mixing basin, the mixing basin is driven by the tipping and mixing motor to rotate at a high speed. At the same time, the vibration motor drives the mixing basin to vibrate up and down to vibrate the material upward and then throw it up. Then, while the mixing basin is rotating, each support rod below moves in the track groove. When the support rod encounters an arc-shaped protrusion or depression, the side of the mixing basin is lifted or lowered, thereby generating a yaw and producing a mixing effect "similar" to tipping for the material in the mixing basin. Therefore, the structure of this tipping and mixing device enables the material in the mixing basin to be simultaneously subjected to the combined action of several effects, producing a tipping and mixing effect similar to that of a wok. This multi-force cooperation method can make the movement path of the powder in the powder mixing platform more complex and diverse. Compared with the conventional vibration mixing method, the mutual interpenetration and mixing of the powders are more sufficient, thus achieving a higher powder mixing uniformity. For example, when mixing some powders with large particle size differences or powders that are prone to agglomeration, the new invention can better break the agglomerates and make the large and small particles evenly distributed. Therefore, it can greatly improve the uniformity and effectiveness of the powder mixing.

[0045] Furthermore, multiple vibration motors are annularly and evenly arranged and installed around the lower surface of the mixing basin. In this way, each vibration motor is connected to the control center. The control center can control each vibration motor to vibrate simultaneously through the internal program to provide an upward vibration effect for the mixing tray at the same time, or can control each vibration motor to vibrate sequentially in a single cycle to provide an upward vibration effect for one side of the mixing tray sequentially in a cycle. Therefore, it can better provide sufficient up and down vibration mode selection for the mixing of the mixing basin. Coupled with the combined movement of yaw and rotation, a better mixing effect is produced.

[0046] Furthermore, a connecting column made of elastic material is fixed downwardly provided in the middle of the lower end of the mixing bowl, and the universal joint is installed at the lower end of the connecting column and connected downwardly to the mixing shaft. In this way, the connecting column provides sufficient elasticity so that the mixing bowl can better achieve up and down vibration and left and right deflection, avoiding the restriction of vibration and deflection caused by rigid connection.

[0047] Furthermore, an elastic edge ring made of elastic material is extended upward and outward from the upper edge of the mixing bowl, and the upper edge of the elastic edge ring fits the inner cavity of the shell. This better ensures that the upper powder can fall into the mixing bowl better and will not fall out from the edge gap, and can also ensure that the mixing bowl has enough space and room to directly swing and shake the material in the inner cavity of the shell, so as to avoid the powder dust from overflowing and affecting environmental hygiene. In implementation, the elastic edge ring can be made of rubber material.

[0048] Furthermore, the shell is fixed on a support frame, the base is installed and fixed on a horizontally arranged lifting plate, the end of the lifting plate can be slidably engaged with the lifting guide rail vertically arranged on the support frame, and a lifting control mechanism is also provided on the support frame and connected to the lifting plate.

[0049] In this way, the lifting control mechanism can control the lifting movement of the lifting plate, and after the lifting plate rises, the mixing bowl is in the inner cavity of the shell and receives and mixes the materials. When the powder materials are mixed in the mixing bowl, the lifting plate can be controlled to descend, so that the mixing bowl is exposed downward from the shell, which is convenient for discharging.

[0050] Furthermore, the lifting control mechanism includes a vertically arranged synchronous belt mechanism, the synchronous belt mechanism includes a pair of vertically arranged synchronous belt pulleys and a synchronous belt wound on the synchronous belt pulleys, the synchronous belt pulleys are drivingly connected to a lifting motor, and the synchronous belt is fixedly connected to the lifting plate. This has the characteristics of simple structure and stable and reliable lifting control.

[0051] Furthermore, a detachable material holding basin is fitted in the mixing basin, a clamping strip is protruding outwardly from the outer surface of the material holding basin, and a clamping groove is correspondingly provided on the inner surface of the mixing basin for the clamping strip to be inserted and matched.

[0052] In this way, it is convenient to directly take out the material holding basin when discharging the material and obtain the recycled powder for reuse.

[0053] In summary, the present invention can better realize powder recycling with less powder loss, higher powder recovery quality, convenient operation, clean and tidy on-site environment, etc., which better saves the overall cost of 3D printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 Schematic diagram of the overall structure of the 3D printing powder recovery and processing system used in the embodiment of the present invention.

[0055] Figure 2 is Figure 1 The structural schematic diagram of the powder suction device for 3D printing alone in

[0056] Figure 3 is Figure 1 The structural schematic diagram of the powder crushing and screening device for 3D printing alone in

[0057] Figure 4 is Figure 3 The structural schematic diagram of the separate crushing mechanism and screening mechanism in

[0058] Figure 5 is Figure 1 The structural schematic diagram of the powder mixing device for 3D printing alone in after removing the support frame and the lifting control mechanism. Some components in the figure are in a disassembled and separated state to better show the structure of the remaining parts.

[0059] Figure 6 is Figure 5 The three-dimensional structural schematic diagram of the remaining components in after removing the protective gas device, split vertically and horizontally and half-sectioned.

[0060] Figure 7 is Figure 6 The three-dimensional structural schematic diagram of the components of the separate material tumbling and mixing device part after being split vertically and horizontally.

[0061] Figure 8 is Figure 5 The structural schematic diagram of the separate protective gas device in

[0062] Figure 9 is Figure 1 The structural schematic diagram of the separate support frame and the lifting control mechanism in Specific embodiments

[0063] The present invention will be further described in detail below in conjunction with specific embodiments.

[0064] Specific embodiments: A method for recycling 3D printing powder, characterized in that after printing is completed, the unformed powder in the forming cylinder is sent to a closed treatment container by suction, and then after being crushed and screened, a part of the unprinted powder new material is added, and then it is mixed evenly and dried before discharging for repeated printing use.

[0065] In this way, in this method, the unformed powder after printing is first sucked away by suction, and the printed components can be discharged after the powder is sucked away, making it more convenient to take out the components. The sucked away powder is crushed and screened, and the part of the powder that has been compacted due to contamination with a small amount of printing solidification material can be crushed and recycled. The powder particle size requirements are guaranteed by screening, so the powder loss is greatly reduced. Then a certain proportion of new powder material is added for mixing, which ensures a high quality of powder recovery and better guarantees the quality of product formation. Finally, the evenly mixed powder is dried to remove the excess water absorbed, and it can be used for secondary printing. Therefore, there are the characteristics of small powder loss and high powder recovery quality.

[0066] In practice, the added mass ratio of new powder is in the range of 30%-50%. Using new powder in this range can ensure that the printed powder has sufficient recycling value and the mixed powder has sufficient printing quality.

[0067] In this embodiment, the method is implemented by a 3D printing powder recovery and processing system, see Figure 1-9 As shown, the 3D printing powder recovery and processing system includes a 3D printing powder suction device, a 3D printing powder crushing and screening device, and a 3D printing powder mixing device which are connected in sequence.

[0068] Specifically, in the present method, the suction process is realized by a 3D printing powder suction device, which includes a shell 1 with a closed container structure, a suction tube 2 is provided at the upper end of the shell 1 and connected to the outside, a powder outlet 3 is provided downward at the lower end of the shell 1, a powder outlet switch is provided at the powder outlet 3, an airflow outlet is also provided on one side of the shell and connected to the outside with an airflow channel 4, a filter 5 with a mesh smaller than the powder particle size is provided at the airflow outlet, and a fan 6 is provided in the airflow channel 4.

[0069] In this way, when the 3D printing powder suction device is working, the powder outlet switch is first kept closed, and then the fan is started to make the suction tube generate suction, so that the powder in the forming cylinder of the printing device can be quickly sucked into the inner cavity of the shell, and the air flow is discharged through the air flow channel. The powder is stored in the device, and when subsequent process operations are required, the powder outlet switch is opened to leak the powder.

[0070] Wherein, the straw 2 is a corrugated tube, so that the straw has flexibility and can better complete the suction of powder.

[0071] The outer shell 1 and the inner cavity are in a rectangular structure as a whole, and the powder outlet at the lower end is a matching rectangle.

[0072] This makes the powder outlet of the powder suction device match the shape of the screening basket in the subsequent crushing and screening device, so that the powder falls from the powder outlet of the powder suction device into the screening basket more evenly, facilitating the subsequent crushing and screening.

[0073] Among them, the powder outlet switch includes a powder baffle 7 horizontally arranged at the powder outlet. The powder baffle 7 is detachably installed on the insertion interface on the inner wall of the powder outlet and has a plugging handle end exposed from the insertion interface.

[0074] In this way, the powder can be made to fall neatly and evenly from the powder outlet to the screening basket of the crushing and screening device in a plugging and unplugging manner, facilitating the subsequent crushing and screening.

[0075] Specifically, in this method, the crushing and screening process is realized by a 3D printing powder crushing and screening device. The 3D printing powder crushing and screening device includes a screening box 10. At the upper end of the screening box 10, there is a screening box inlet 11 for the powder to enter, and at the lower end, there is a screening box outlet 12 for the powder to discharge. In the inner cavity of the screening box, there are a crushing mechanism and a screening mechanism. The screening mechanism includes a horizontally arranged screening basket 13. The screening basket 13 is located in the upper part of the inner cavity of the screening box and is below the screening box inlet. The four corner positions of the screening basket 13 are fixed on the upper end wall of the inner cavity of the screening box by vertically upward spiral springs 14. The screening device is connected to a vibrator, and the lower surface of the screening basket is a horizontally fixed screen 15.

[0076] In this way, the powder falls from the screening box inlet into the screening box and then onto the screening basket. After being crushed by the crushing mechanism, the screening is realized by driving the screening basket by the vibrator. During screening, the screening basket vibrates driven by the vibrator, and the vibration effect is amplified by the four spiral springs at the corners, improving the screening efficiency. In this way, through screening, it is ensured by the screen that the particle size of the falling powder can meet the regeneration requirements, realizing the efficient regeneration screening treatment of 3D printing powder.

[0077] The screening basket 13 is rectangular as a whole, and the crushing mechanism includes a crushing roller 16 arranged in the screening basket along the width direction, and ear plates 17 along the length direction are upwardly arranged at the side edges of the screening basket in the width direction, and horizontal guide grooves 18 are opened on the ear plates along the length direction. The circumferential surface of the crushing roller 16 is provided with crushing protrusions 19 of equal height in rows along the axial direction, and each row of crushing protrusions 19 is evenly distributed in the circumferential direction. The roller shafts at both ends of the crushing roller 16 are also sleeved with an elastic roller sleeve 20, which is fitted in the guide groove 18. The outer end of the roller shaft is rotatably mounted vertically on a connecting rod 21 arranged obliquely downward through a bearing, and the lower end of the connecting rod 21 is rotatably connected to the outer end of a crank 22 to form a crank-connecting rod mechanism, and the crank is connected to a crushing and screening motor 23 located below one end of the screening basket, and the crank-connecting rod mechanism applies a downward pre-tension to the screening basket 13.

[0078] In this way, the crushing and screening motor drives the roller shaft to roll horizontally in the guide groove through the crank connecting rod mechanism. Since the crank connecting rod mechanism applies a downward pre-tension to the screening basket, the pre-tension is offset by the action of four spiral springs to keep the screening basket balanced. In this way, since the roller shaft is matched with the guide groove through the elastic roller sleeve with elasticity, the height of the crushing protrusion on the crushing roller matches the elastic deformation size of the elastic roller sleeve. When the crushing roller rotates until the crushing protrusion is facing downward and in contact with the screen surface, the elastic roller sleeve is in a state of no stress in the middle position (at this time, the pre-tension of the crank connecting rod directly acts on the screen and the screening basket downward through the crushing roller and the crushing protrusion). When the crushing roller continues to rotate, the crushing protrusion rotates forward and disengages from the contact with the screen surface. The screen and the screening basket reset upward under the action of the spiral spring, and the elastic roller sleeve switches to an extrusion stress deformation state (at this time, the pre-tension of the crank connecting rod acts on the screening basket through the elastic roller sleeve). In this way, the crushing roller switches between two states repeatedly when rolling, driving the screen to vibrate up and down. At the same time, since the crushing roller itself is rolling forward when switching between the two states, the friction force component generated by its rolling will cause a component force in the horizontal direction and produce a horizontal swing. Therefore, the rolling of the crushing roller itself in the above-mentioned device can produce a crushing effect on the powder. At the same time, the coordinated movement effect produced by the mutual cooperation between the various structures makes the crushing roller form a vibrator while rolling, and drives the screen to produce a composite vibration effect of up and down vibration and front and back swing superimposed, greatly improving the screening efficiency and screening effect. The setting of the elastic roller sleeve allows the above-mentioned composite vibration effect to be better realized, while also ensuring the stability of the rolling process of the crushing roller itself during the composite vibration process of the screening basket driven by the crushing roller, and avoiding the influence of the reverse transmission of vibration to the motor to the greatest extent, thereby extending the life of the motor. Therefore, the crushed powder can be better vibrated and screened while ensuring the smooth and durable operation of the device.

[0079] The screening box 10 is in a rectangular structure as a whole.

[0080] Among them, the crushing and screening motor 23 is installed on the motor bracket located below one end of the screening basket, which facilitates the installation and setting of the motor.

[0081] Among them, the screening box inlet includes a first screening box inlet 11 for sealing and docking with the powder outlet of the 3D printing powder suction device.

[0082] In this way, after the 3D printing powder suction device finishes sucking the powder, the powder is directly input into the screening box through the first screening box inlet, avoiding the powder from spilling out and affecting the environmental hygiene.

[0083] Among them, the screening box inlet further includes a second screening box inlet 24, and a second screening box inlet switch cover is arranged at the upper end of the second screening box inlet 24.

[0084] This is because the 3D printing device usually has a device for setting overflow powder collection, such as an overflow powder tank. The amount of powder in this part is less and it is not convenient to directly suck it with a straw. Therefore, the second screening box inlet switch cover can be directly opened to pour this part of the powder into the screening box for screening treatment.

[0085] Among them, a conical discharge hopper 25 is arranged downward at the lower end of the screening box, and a screening box outlet 12 is formed below the discharge hopper, which is more convenient for the screening box to discharge materials.

[0086] Specifically, in this method, the steps of adding powder new material for mixing and drying are realized by a 3D printing powder mixing device. The 3D printing powder mixing device includes a vertically cylindrical shell 30. The upper end of the shell 30 is respectively provided with a recovered powder interface 31 and a newly added powder interface 32 opening upward. A sprinkling and mixing device is further arranged in the upper part of the inner cavity of the shell, and a jolting and mixing device and a discharging device are arranged in the lower part of the shell.

[0087] In this way, the recovered powder enters from the recovered powder inlet, and the newly added powder enters from the newly added powder inlet. The two kinds of powders are mixed in the inner cavity of the shell through two different principle mixing methods of the sprinkling and mixing device and the jolting and mixing device in sequence, so that they are better mixed evenly and then discharged, which better improves the mixing efficiency and mixing quality.

[0088] Among them, an electric heating module interlayer 33 is further arranged in the shell 30. In this way, the powder inside can be heated by an electric heating method, which can quickly realize drying and avoid the influence of moisture contained in the powder on subsequent use.

[0089] Among them, a protective gas device 34 is also installed on the housing. The protective gas device 34 includes an air extraction joint 35 and an air inlet joint 36 exposed in the inner cavity wall of the housing. The air extraction joint is externally connected to an air extraction pipeline and is used to connect to an air extraction fan, and the air inlet joint is externally connected to an air inlet pipeline and is used to connect to a protective gas cylinder. Control valves 37 are also installed on the air extraction pipeline and the air inlet pipeline.

[0090] In this way, the control valve is connected to the control center. When some powder materials need to isolate air during the heating and drying process, the air extraction joint can be controlled to extract air from the inner cavity of the housing, and then the air inlet joint can be controlled to introduce protective gas to isolate the internal air to form an atmosphere protection, avoiding oxidation and denaturation of the powder materials during heating. During implementation, an oxygen sensing probe can be further installed on the inner wall of the housing and connected to the control center to better achieve control.

[0091] Among them, upward connecting feed channels are respectively arranged on the recycled powder interface 31 and the newly added powder interface 32, and a feed control switch is arranged at the lower end position of the feed channels. This facilitates the control of the feeding.

[0092] Among them, the feed control switch includes a feed switch baffle 40. The feed switch baffle 40 is horizontally arranged in a plug-in interface on one side of the feed channel in a pullable manner. The outer end of the feed switch baffle can be inserted and pulled out of the plug-in interface and is connected to a feed control electric push rod device 41 located at the upper end of the housing. A weighing sensor 42 is also arranged on the feed switch baffle 40. During implementation, the feed control electric push rod device 41 is connected to a weight transmitter 43 located at the upper end of the housing.

[0093] In this way, after the powder materials enter the feed channel, they can be weighed by the weighing sensor. After meeting the requirements, the electric push rod device is controlled to pull the feed switch baffle to make the powder materials fall into the inner cavity of the housing, facilitating the control of the feeding ratio of the recycled powder and the newly added powder. During implementation, the output end of the weighing sensor is connected to the input end of the weight transmitter (or directly connected to the control center), and the output end of the weight transmitter is connected to the input end of the electric push rod. Parameters can be set for the weight transmitter, and the output signal of the weighing sensor will be compared with the set value in the weight transmitter. When the weight reaches the set weight, the weight transmitter will input a corresponding control signal to the electric push rod to make the electric push rod work.

[0094] Among them, a dust-proof cover 44 is also arranged at the upper end of the housing. The upper end of the feed channel at the upper end of the recycled powder interface 31 passes through the dust-proof cover 44 and is used to dock with the outlet of the screening box of the 3D printing powder crushing and screening device. The upper end of the feed channel above the newly added powder interface 32 passes through the dust-proof cover and is provided with an outward folding section 45, and a switch cover 46 is arranged at the upper end of the folding section.

[0095] In this way, it is convenient to achieve dust prevention during feeding and ensure environmental sanitation.

[0096] Wherein, the scattering and mixing device includes a scattering and mixing shaft 50 vertically installed in the middle of the upper end of the shell cavity, the upper end of the scattering and mixing shaft 50 can rotatably pass through the shell 30 and is connected to a scattering and mixing motor 51 installed at the upper end of the shell, a plurality of first mixing blades 52 are evenly arranged along the circumference at the upper position of the scattering and mixing shaft 50, the downward projections of the recovered powder interface 31 and the newly added powder interface 32 fall within the rotation range of the first mixing blade 52, a blanking funnel 53 is arranged on the outside of the first mixing blade 52, the upper end of the blanking funnel 53 is fixed at the upper end of the shell cavity and the lower end outlet is suspended, the lower end position of the scattering and mixing shaft 50 exceeds the lower end outlet position of the blanking funnel downward, and a plurality of second mixing blades 54 are evenly installed along the circumference at the lower end of the scattering and mixing shaft, and the downward projection of the lower end outlet of the blanking funnel falls within the rotation range of the second mixing blade 54.

[0097] In this way, when the device is in use, the throwing and mixing motor drives the first mixing blade and the second mixing blade to rotate at high speed. After the new and old powders enter the inner cavity of the shell from the powder recovery interface and the new powder interface, they fall onto the first mixing blade, are scattered and mixed in all directions by the first mixing blade rotating at high speed, and are then gathered downward by the dropping funnel and fall onto the second mixing blade again, and are scattered and mixed in all directions by the second mixing blade rotating at high speed and fall into the lower part of the inner cavity of the shell. Compared with the conventional mixing method that easily produces a mixing dead angle, the present device is a dynamic process in which the powder falls in the air, and is repeatedly scattered, mixed and thrown by two blades, thereby realizing an efficient and fast dynamic mixing process and having a good mixing effect. In addition, in the process of the throwing and mixing device relying on the rotating blades to scatter the powder, the string-like powder particles that are difficult to be removed by screening due to the adhesion of the solidified material in one direction can be scattered, so that the adhesion is broken, the regeneration quality of the powder is better improved, and the forming effect during reuse is ensured. During implementation, the first mixing blade and the second stirring blade are in the shape of long thin slices and are tilted toward one side of the rotation direction, and the front edge of the blade is blade-shaped. In this way, the powder can be dispersed and moved around, and the powder mass can be better chopped and dispersed.

[0098] Among them, two rows of guide protrusions are symmetrically arranged on the inner side of the blanking funnel. The upper ends of the guide protrusions are located in the middle of the left and right sides of the inner side of the blanking funnel, and the lower ends extend along the spiral to the lower edge of the other side of the inner side of the blanking funnel.

[0099] This is because when the old and new powder materials enter the inner cavity of the housing from the recycled powder interface and the newly added powder interface respectively and are scattered onto the blanking funnel by the first mixing blade, there is still a large directionality, that is, the old and new powder materials will relatively concentrate and fall to one side. Therefore, after setting the above diversion protrusions, a part (about half) of the powder scattered and falling to one side of the funnel can be guided by the diversion protrusions to fall on the other side of the funnel. Then, after being scattered again by the second mixing blade, the mixing uniformity is greatly improved.

[0100] During implementation, the height of the diversion protrusion is gradually increased from top to bottom. In this way, the powder diversion effect can be better guaranteed.

[0101] Among them, the tipping and mixing device includes a mixing basin 55 located at the lower end of the inner cavity of the housing. The mixing basin 55 has an upward opening and a circular shape matching the inner cavity wall of the housing. The middle of the lower end of the mixing basin 55 is supported and installed at the upper end of a vertically arranged tipping and mixing rotating shaft 57 through a universal joint 56. The lower end of the tipping and mixing rotating shaft 57 is connected to a tipping and mixing motor 58 installed on the base. A vibration motor 59 is also installed on the mixing basin 55. The vibration motor 59 is used to output vertical vibration to the mixing basin. A plurality of support rods 60 are also arranged downward at the peripheral position of the lower surface of the mixing basin. The support rods 60 are evenly distributed in a ring centered on the tipping and mixing rotating shaft. The support rods 60 have an upper half section and a lower half section that are inserted and matched to form a sleeve structure. A vertical support spring is arranged inside the upper half section and the lower half section to form a vertical elastic support connection. The upper end of the upper half section is rotatably installed on the lower surface of the mixing basin 55 through a hinge joint 61. The hinge axis direction of the hinge joint 61 is arranged along the direction perpendicular to the diameter of the mixing basin. The lower end of the lower half section is rotatably supported and installed in a circular track groove 63 on the upper surface of a base 68. At least one arc-shaped protrusion 64 or depression is arranged on the groove bottom surface of the track groove 63.

[0102] In this way, after the powder material falls into the mixing basin, the mixing basin is driven by the tipping and mixing motor to rotate at a high speed. At the same time, the mixing basin is driven by the vibration motor to vibrate up and down, throwing the material upward. Then, while the mixing basin is rotating, each support rod below moves in the track groove. When the support rod encounters an arc-shaped protrusion or depression, the side of the mixing basin is lifted or lowered, thereby generating a yaw and producing a mixing effect "similar" to tipping for the material in the mixing basin. Therefore, the structure of this tipping and mixing device enables the material in the mixing basin to be simultaneously affected by several combined effects, producing a tipping and mixing effect similar to that of a wok. This multi-force cooperation method can make the movement path of the powder in the powder mixing platform more complex and diverse. Compared with the conventional vibration mixing method, the powder is more fully interpenetrated and mixed with each other, thus achieving a higher powder mixing uniformity. For example, when mixing some powders with large particle size differences or prone to agglomeration, the new invention can better break the agglomerates and make the large and small particles evenly distributed. Therefore, it can greatly improve the uniformity and effectiveness of powder mixing.

[0103] Among them, a plurality of the vibration motors 59 are annularly and evenly arranged and installed around the lower end surface of the mixing basin. In this way, each vibration motor is connected to the control center. The control center can control each vibration motor to vibrate simultaneously through the internal program, providing an upward vibration effect for the mixing tray at the same time, or can control each vibration motor to vibrate in sequence and individually in a cycle, providing an upward vibration effect for one side of the mixing tray and cycling in sequence. Therefore, it can better provide sufficient up and down vibration mode selection for the mixing of the mixing basin. Coupled with the combined movement of yaw and rotation, a better mixing effect is produced.

[0104] Among them, a connecting column 65 made of an elastic material is fixedly arranged downward in the middle of the lower end of the mixing basin 55. The universal joint is installed at the lower end of the connecting column 65 and is connected downward to the tipping and mixing rotating shaft. In this way, the connecting column provides sufficient elasticity so that the mixing basin can better achieve up and down vibration and left and right yaw, avoiding the limitation of vibration and yaw caused by rigid connection. During implementation, the elastic material can be made of rubber material.

[0105] Among them, an elastic edge ring 66 made of an elastic material extends outward and upward from the upper edge of the mixing basin (and / or the material receiving basin), and the upper edge of the elastic edge ring 66 is attached to the inner cavity of the housing 30. In this way, it can better ensure that the upper powder material can better fall into the mixing basin and will not fall out from the edge gap, and can also ensure that the mixing basin has enough space and room to directly achieve yaw and tipping in the inner cavity of the housing, avoiding the overflow of powder dust and affecting environmental hygiene. During implementation, the elastic edge ring can be made of rubber material.

[0106] Among them, the housing 30 is fixed on a support frame 67, and the base 68 is installed and fixed on a horizontally arranged lifting plate 69. The end of the lifting plate 69 is slidably clamped and fitted on a lifting guide rail 70 vertically arranged on the support frame. A lifting control mechanism is also arranged on the support frame 67 and is connected to the lifting plate.

[0107] In this way, the lifting control mechanism can control the lifting movement of the lifting plate. After the lifting plate rises, the mixing basin is located in the inner cavity of the housing and can receive and mix materials. When the powder materials are mixed in the mixing basin, the lifting plate can be controlled to descend, so that the mixing basin is lowered to expose outside the housing, facilitating discharging.

[0108] Among them, the lifting control mechanism includes a vertically arranged synchronous belt mechanism. The synchronous belt mechanism includes a pair of vertically arranged synchronous belt wheels 72 and a synchronous belt 71 wound around the synchronous belt wheels. The synchronous belt wheels are in transmission connection with a lifting motor 73, and the synchronous belt is fixedly connected to the lifting plate. This has the characteristics of simple structure, stable and reliable lifting control.

[0109] Among them, a detachable material receiving basin 75 is fitted inside the mixing basin 55. The outer surface of the material receiving basin protrudes outward with clamping strips, and corresponding clamping grooves are arranged on the inner surface of the mixing basin for the clamping strips to be inserted and fitted.

[0110] In this way, it is convenient to directly take out the material receiving basin when discharging to obtain the regenerated powder materials for reuse.

Claims

1. A method for recycling 3D printing powder, characterized in that: After printing is completed, the unformed powder in the forming cylinder is sucked into a closed processing container, and then after crushing and screening, some unprinted powder new material is added, and then mixed evenly and dried before being discharged for repeated printing.

2. The 3D printing powder recycling method according to claim 1, characterized in that: The added mass ratio range of powder new material is 30%-50%.

3. The 3D printing powder recycling method according to claim 1, characterized in that: The suction process is achieved by a 3D printing powder suction device, which includes a shell with a closed container structure, a suction tube is arranged at the upper end of the shell to connect to the outside, a powder outlet is arranged downward at the lower end of the shell, a powder outlet switch is arranged at the powder outlet, an airflow outlet is also arranged on one side of the shell and connected to the outside to connect to an airflow channel, a filter with a mesh smaller than the powder particle size is arranged at the airflow outlet, and a fan is arranged in the airflow channel.

4. The 3D printing powder recycling method according to claim 3, characterized in that: The straw is a corrugated tube.

5. The 3D printing powder recycling method according to claim 3, characterized in that: The shell and the inner cavity are in a rectangular structure as a whole, and the powder outlet at the lower end is a matching rectangle; The powder outlet switch comprises a powder baffle plate horizontally arranged at the powder outlet, the powder baffle plate is installed on the plug-in interface of the inner wall of the powder outlet in a pull-out manner and has a plug-in handle end exposed from the plug-in interface.

6. The 3D printing powder recycling method according to claim 1, characterized in that: The crushing and screening process is achieved by a 3D printing powder crushing and screening device, which includes a screening box, a screening box inlet for powder to enter is arranged at the upper end of the screening box, and a screening box outlet is arranged at the lower end for powder to be discharged. A crushing mechanism and a screening mechanism are arranged in the inner cavity of the screening box. The screening mechanism includes a horizontally arranged screening basket, which is located at the upper part of the inner cavity of the screening box and below the inlet of the screening box. The four corners of the screening basket are fixed to the upper end wall of the inner cavity of the screening box by means of vertically upward spiral springs. The screening device is connected to the vibrator, and the lower surface of the screening basket is a horizontally fixed screen.

7. The 3D printing powder recycling method according to claim 6, characterized in that: The screening basket is rectangular as a whole, and the crushing mechanism includes a crushing roller arranged in the screening basket along the width direction, and ear plates along the length direction are upwardly arranged on the side edges of the screening basket in the width direction, and horizontal guide grooves are opened on the ear plates in the length direction. The circumferential surface of the crushing roller is provided with crushing protrusions of equal height in rows along the axial direction, and each row of crushing protrusions is evenly distributed in the circumferential direction. The roller shafts at both ends of the crushing roller are also respectively sleeved with an elastic roller sleeve, which fits in the guide groove. The outer end of the roller shaft is rotatably mounted vertically on a connecting rod arranged obliquely downward through a bearing, and the lower end of the connecting rod is rotatably connected to the outer end of a crank to form a crank-connecting rod mechanism, the crank is connected to a crushing and screening motor located below one end of the screening basket, and the crank-connecting rod mechanism applies a downward pre-tension to the screening basket.

8. The 3D printing powder recycling method according to claim 7, characterized in that: The screening box is in a rectangular structure as a whole; The crushing and screening motor is mounted on a motor frame located below one end of the screening basket.

9. The 3D printing powder recycling method according to claim 7, characterized in that: The screening box inlet includes a first screening box inlet for sealingly docking with a powder outlet of a 3D printing powder suction device; The screening box inlet also includes a second screening box inlet, and a second screening box inlet switch cover is arranged at the upper end of the second screening box inlet.

10. The 3D printing powder recycling method according to claim 7, characterized in that: A conical discharge hopper is arranged downwardly at the lower end of the screening box, and a screening box outlet is formed below the discharge hopper.

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