Adjustable powder spreading structure and 3D printing method

Abstract

The invention relates to the technical field of metal 3D printing, and discloses an adjustable powder laying structure and a 3D printing method in order to solve the technical problems that according to conventional 3D printing equipment, scraper replacement operation is complex, box opening operation is needed, consumed time is long, and a forming cabin needs to be inflated again. The outer side of the fixing support is connected with a pressing roller mechanism through a driving system, and a scraper system is arranged on the inner side of the fixing support. The fixing support comprises a top transverse plate and a lateral vertical plate, and a lifting groove is formed in the inner side of the lateral vertical plate and used for vertical displacement of the scraper system along the lifting groove. The scraper system comprises a pair of main rotating discs, a main shaft is fixedly connected to the centers of the inner sides of the main rotating discs, a plurality of scrapers arranged in a circumferential array are arranged between the main rotating discs, and first fixing pins used for axially positioning the scrapers are arranged on the main rotating discs. And due to the design of the main rotating disc and the scrapers arranged in the circumferential array, the scrapers can be rapidly replaced, and the technical problem that box opening and re-inflation are needed for replacing the scrapers is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal 3D printing, and in particular to an adjustable powder spreading structure and a 3D printing method. Background Art

[0002] Selective laser melting (SLM) technology is an important branch of 3D printing that has attracted much attention. Its unique forming principle makes it show significant advantages in manufacturing complex parts. SLM technology discretizes the three-dimensional digital model through dedicated slicing software and converts it into a series of two-dimensional plane geometric figures. Subsequently, the 3D printing equipment relies on a precisely controlled laser system to stack these two-dimensional geometric figures layer by layer through layer-by-layer powder spreading and sintering, and finally forms a complex three-dimensional part. This mold-free manufacturing technology enables SLM to respond quickly to design changes and significantly shorten the product development cycle, which is particularly suitable for small-batch production and customized manufacturing. However, the practical application of SLM technology also faces some challenges that cannot be ignored, one of which is closely related to the long-term service life and maintenance of the powder spreading mechanism and scraper.

[0003] In SLM technology, the powder spreading mechanism plays a vital role. It drives the scraper to reciprocate and spreads the raw material powder evenly on the forming substrate, thus providing a basis for subsequent laser sintering. Whether it is rubber, metal, or ceramic scrapers, after long-term use, they will gradually wear out due to repeated friction with the printed parts and metal powder. This wear will inevitably lead to damage to the edge of the scraper and even form large-area gaps. The wear of the scraper will directly affect the uniformity of the powder spreading, resulting in uneven powder spreading surface. As a result, in the subsequent printing process, the laser cannot act evenly on the entire powder layer, which ultimately leads to poor product metallurgy or missing features of the printed parts, seriously affecting the quality of the finished product.

[0004] In addition to the problem of scraper wear, conventional 3D printing equipment is often only equipped with a single scraper or double scraper setting. Although this setting simplifies the equipment structure, it also brings operational inconveniences. When the scraper wears to a certain extent and affects the powder spreading effect, the operator must pause the printing process, open the forming cabin door of the 3D printing equipment, and manually remove and replace the scraper. This process is not only time-consuming, but also requires multiple manual powder spreading adjustments to ensure that the ideal powder spreading effect can be restored after the scraper is replaced. In addition, since the forming chamber is usually filled with protective gases such as argon, a large amount of protective gas will be lost during the replacement of the scraper. In order to restore the low-oxygen environment in the cabin, a large amount of protective gas must be filled again, which not only increases production costs, but also prolongs the downtime of the equipment.

[0005] A more serious problem is that for some thin-walled parts, long printing pauses may lead to uneven distribution of thermal stress, which in turn may cause misalignment during the next forming process, and even lead to the scrapping of the entire part. This series of problems not only affects the forming efficiency of 3D printing equipment, but also limits the widespread application of SLM technology to a certain extent.

[0006] The above drawbacks have seriously restricted the large-scale promotion and use of 3D printing equipment, and also limited the further improvement of the forming efficiency of 3D printing equipment. How to overcome these difficulties to improve the stability and forming efficiency of SLM technology has become an important issue that needs to be solved in the field of 3D printing. Summary of the invention

[0007] The purpose of the present invention is to provide an adjustable powder spreading structure and a 3D printing method to solve the technical problems that the scraper replacement operation of conventional 3D printing equipment is complicated, requires unpacking operation, is time-consuming, and the forming chamber needs to be re-inflated.

[0008] To achieve the above-mentioned purpose, as one aspect of the present invention, an adjustable powder spreading structure is provided, including an L-shaped fixed bracket symmetrically distributed on the left and right, the outer side of the fixed bracket is connected to a pressure roller mechanism through a driving system, and a scraper system is arranged on the inner side of the fixed bracket; the fixed bracket includes a top horizontal plate and a lateral vertical plate, the top horizontal plate is provided with bolt holes fixedly connected to a moving mechanism in a 3D printing device, and the inner side of the lateral vertical plate is provided with a lifting groove for vertical displacement of the scraper system along the lifting groove; the scraper system includes a pair of main turntables, the inner center of the main turntable is fixedly connected with a main shaft, a plurality of scrapers arranged in a circular array are arranged between the main turntables, and the main turntable is provided with a first fixing pin for axially positioning the scraper.

[0009] Furthermore, a motor system is arranged at the outer center of the main turntable, and the motor system is fixedly connected to a walking system that cooperates with the lifting slot for vertical displacement.

[0010] The combination of the motor system and the travel system enables the main turntable to move precisely in the vertical direction. This design increases the adjustability and flexibility of the scraper system, and can fine-tune the position of the scraper according to actual needs. Especially during the 3D printing process, the height and angle of the scraper can be automatically adjusted without stopping the equipment, further improving the accuracy and uniformity of the powder spreading, ensuring the continuity and quality stability of the forming process.

[0011] Furthermore, the pressure roller mechanism includes a connecting frame distributed on the outside of the lateral vertical plate, a pin hole is arranged on the outside of the lateral vertical plate, a second fixing pin is arranged passing through the first end of the connecting frame to axially position the connecting frame in the pin hole, a pressure roller is arranged between the second ends of the connecting frame, and a third fixing pin is arranged for axially positioning the pressure roller.

[0012] The pressure roller can effectively compact the laid powder layer to ensure the flatness and density uniformity of each layer of powder. This can reduce the forming defects caused by uneven powder during the printing process and improve the surface quality and mechanical properties of the final product.

[0013] Furthermore, an up-and-down driving mechanism and a connecting rod mechanism driven by the up-and-down driving mechanism are arranged on the outer side of the lateral vertical plate. The connecting rod mechanism is connected to the connecting frame. The up-and-down driving mechanism and the connecting rod mechanism constitute a driving system.

[0014] The combination of the upper and lower drive mechanisms and the connecting rod mechanism constitutes a flexible drive system that can accurately adjust the height of the pressure roller during the powder spreading process. This design allows for quick adjustment of different layer thicknesses and powder characteristics, thereby achieving adaptive adjustment for different printing materials and printing accuracy requirements. This height adjustability helps reduce printing problems caused by changes in material properties or uneven powder distribution, further improving the versatility and applicability of 3D printing equipment.

[0015] As another aspect of the present invention, a 3D printing method is provided, comprising the following steps:

[0016] Step S1, installing the forming substrate into the 3D printing device and filling the forming chamber with powder;

[0017] Step S2, after compacting the powder, adjust the scraper system of the fixed support to an appropriate position, and remove the scraper system;

[0018] Step S3, installing the scraper to the main turntable, setting the scraper and the main turntable to be rigidly connected to ensure that the scraper is fixed and does not rotate;

[0019] Step S4, reinstall the scraper system onto the fixed bracket, adjust the motor system and the travel system to move downward along the lifting slot to an appropriate position, so that the lower part of the scraper is substantially in contact with the upper plane of the forming substrate, and adjust the position so that the scraper maintains a predetermined distance D from the forming substrate;

[0020] Step S5, the pressure roller is mounted on the connecting frame 31 through the third fixing pin 34, and then mounted on the fixing bracket through the second fixing pin, and connected to the upper and lower driving systems on the side of the fixing bracket;

[0021] Step S6, adjusting the position of the pressing roller so that the distance between the bottom of the pressing roller and the forming substrate is d, d<D, and the range of Dd is 0.01-0.05 mm;

[0022] Step S7, closing the forming cabin door, filling with protective gas, and starting substrate heating;

[0023] Step S8, adjusting the positions of the scraper and the pressure roller, and the motor system and the travel system move upwards by an appropriate distance T, T>D;

[0024] Step S9, powder falls to the front of the scraper through the raw material bin;

[0025] Step S10, moving the adjustable powder spreading structure, spreading the powder with a scraper and compacting the powder layer with a roller;

[0026] Step S11, after the powder spreading is completed, the adjustable powder spreading structure is moved to the other side of the equipment to avoid damaging the laid powder layer;

[0027] Step S12, after the oxygen content and temperature in the cabin meet the standards, laser sintering printing is started until the current layer is printed;

[0028] Step S13, feeding powder and laying the second layer of powder, compacting the powder, the adjustable powder laying mechanism rises after laying the powder, then moves to the left to receive the powder, and the laser emits light to sinter the second layer, and the cycle is repeated in sequence;

[0029] Step S14, after printing is completed, cool and remove the formed parts.

[0030] Furthermore, in step S13, the following exception handling strategy is set:

[0031] If there is no abnormality during the printing process, or the scraper is slightly worn, sintering will be continued according to the established printing procedure until the printing is completed;

[0032] If the scraper is worn out, start the motor system, rotate the main turntable to adjust the scraper position, and ensure that the distance between the scraper and the forming substrate is kept at the set value D to maintain the consistency and uniformity of the powder spreading surface;

[0033] If the scraper is severely worn and cannot ensure smooth powder spreading, continue to rotate the main turntable and switch to the spare scraper to ensure that the distance to the forming substrate remains at D. There is no need to pause printing or open the cabin door, thus saving time and protective gas and improving printing efficiency.

[0034] Furthermore, with the fixed bracket as a reference, a second pressing roller mechanism is provided which is mirror-symmetrical to the pressing roller mechanism.

[0035] The adjustable powder spreading structure and 3D printing method provided by the present invention have the following advantages:

[0036] The adjustable powder spreading structure of the present invention adopts a pair of main rotating discs and a plurality of scrapers arranged in a circular array, so that the scrapers can be quickly replaced. By controlling the forward and reverse rotation of the main rotating disc, a new scraper can be quickly rotated to the working position, avoiding the tedious operations of unpacking, pausing printing, and replacing the scraper in traditional equipment, greatly shortening the equipment downtime.

[0037] Since the present invention can realize the scraper replacement operation without opening the forming cabin door, the loss of protective gas is avoided, and the forming cabin does not need to be re-filled. This design effectively saves the use of protective gas, reduces operating costs, and significantly reduces the time required for scraper replacement.

[0038] The adjustable powder spreading structure of the present invention can ensure that the scraper position is quickly switched to a new one after the scraper is worn, and the flatness and uniformity of the powder spreading are always maintained, thereby improving the forming quality and forming efficiency. Especially for thin-walled parts, the printing pause time is reduced, the risk of misalignment and scrapping is reduced, and the precision and quality stability of the formed products are further improved.

[0039] In summary, the present invention successfully solves the technical problems of complicated and time-consuming scraper replacement operation and the need to re-inflate the forming chamber in traditional 3D printing equipment through the design of an adjustable powder spreading structure, thereby greatly improving the working efficiency and product forming quality of the 3D printing equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A three-dimensional diagram of the adjustable powder spreading structure provided by the present invention;

[0041] Figure 2 A front view of the adjustable powder spreading structure provided by the present invention;

[0042] Figure 3 A schematic diagram of the structure of the fixing bracket provided by the present invention;

[0043] Figure 4 A schematic diagram of the structure of the pressure roller provided by the present invention;

[0044] Figure 5 A three-dimensional diagram of the scraper system provided by the present invention;

[0045] Figure 6 A cross-sectional view of a scraper system provided by the present invention;

[0046] Figure 7 This is a schematic diagram of the one-way powder spreading principle of the adjustable powder spreading mechanism provided by the present invention.

[0047] In the figure: 10, fixed support; 20, scraper system; 30, roller mechanism; 50, forming substrate; 60, powder;

[0048] 11. Bolt hole; 12. Lifting slot; 13. Up and down driving mechanism; 14. Connecting rod mechanism; 15. Pin hole; 21. Main turntable; 22. Scraper; 23. Motor system; 24. Main shaft; 25. First fixed pin; 26. Travel system; 31. Connecting frame; 32. Pressure roller; 33. Second fixed pin; 34. Third fixed pin. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0050] See also Figures 1 to 6 The present invention provides an adjustable powder spreading structure, including a pair of L-shaped fixed brackets 10 symmetrically distributed on the left and right, the outer side of the fixed bracket 10 is connected to a pressure roller mechanism through a driving system, and the inner side of the fixed bracket 10 is provided with a scraper system 20.

[0051] The fixed bracket 10 includes a top horizontal plate and a lateral vertical plate. The top horizontal plate is provided with a bolt hole 11, which is fixedly connected to the motion mechanism in the 3D printing device by bolts to prevent the scraper from shaking, falling off, tilting, etc. when spreading powder. The fixed bracket 10 is used to provide support for the scraper system 20 and the pressure roller mechanism 30 to protect their normal operation. The reciprocating motion of the motion mechanism transmits the running speed and direction to the fixed bracket 10 through the horizontal plates on the left and right sides. The scraper system is loaded on the fixed bracket, which in turn drives the scraper to reciprocate and spread powder, thereby realizing the precise operation of the powder spreading action.

[0052] The inner side of the lateral vertical plate is provided with a lifting groove 12 for the scraper system 20 to rise or fall along the lifting groove 12, providing an operation channel for the scraper system 20 to be replaced, raised, or lowered. The lifting groove 12 is used to achieve precise operation of the scraper system 20 when it rises or falls.

[0053] The scraper system 20 includes a pair of main turntables 21 , with a main shaft 24 fixedly connected to the inner center of the main turntable 21 , a scraper 22 is arranged between the main turntables 21 , and first fixing pins 25 for fixing the scraper 22 are arranged in a circular array along the edge of the main turntable 21 .

[0054] The main shaft 24 is used to provide strength support for the entire scraper system 20. Its length is consistent with or slightly larger than the width of the 3D printing cylinder. By adjusting its length, different 3D printing devices and different printing formats can be effectively spread. Moreover, it is closely matched with the main turntable through bolts to achieve synchronous movement.

[0055] The first fixing pin 25 is mainly used to fix the scraper 22 on the main rotating disk 21 to prevent the scraper 22 from falling off.

[0056] On the one hand, if the first fixing pin 25 is a pin. In this way, when the main turntable 21 rotates, the scraper 22 can rotate synchronously therewith. Because the scraper 22 is not rigidly connected to the main turntable 21, it can also rotate around its own axis under the action of its own gravity. In this way, the scraper 22 runs to spread powder. As the powder spreading structure runs, the scraper 22 can further rotate under the action of friction when rubbing against the powder bed. Therefore, each part of the scraper 22 in the circumferential direction can effectively achieve the powder spreading effect, and each part in the circumferential direction evenly receives friction loss, thereby increasing the service life of a single scraper. It effectively avoids the pain point that a single scraper of a conventional 3D printer, point contact or surface contact, once the scraper is partially worn, it will be scrapped, and then the scraper has to be replaced. Moreover, the fixation in the form of a pin can effectively reduce the scraper wear for parts printed on a full-width surface. At the same time, because the scraper is rolling friction rather than sliding friction relative to the part, when printing thin-walled parts, or when there are protrusions in the part printing, the friction between it and the part is significantly reduced, which can effectively reduce the risk of part deformation caused by scraper collision.

[0057] On the other hand, if the first fixing pin 25 is a fixing bolt, the scraper 22 is rigidly connected to the main turntable 21. By rotating the main turntable 21, the contact surface between different scrapers 22 and the same scraper 22 and the powder can be adjusted, which can also reduce the wear of the scraper and increase the service life of the scraper 22.

[0058] A motor system 23 is provided at the outer center of the main turntable 21, and the motor system 23 is fixedly connected to a travel system 26, and the motor system 23 rises or falls along the lifting slot 12 through the travel system 26. The motor system 23 is closely connected to the main turntable 21 of the scraper system 20. The forward and reverse rotational motions at different speeds provided by the motor system 23 are transmitted to the main turntable 21, thereby driving the scraper system 20 to rotate forward and reverse at different speeds.

[0059] For example, in one embodiment, the traveling system 26 is a gear, and a tooth groove is provided in the lifting groove 12, so that the lifting or lowering is achieved through a meshing structure.

[0060] The main rotating disc 21 is used to provide support for the placement of the scraper 22. By reasonably setting the size and spacing of the scrapers, multiple scrapers can be evenly or unevenly distributed on the main rotating disc 21. Moreover, it can be rotated forward or reversely by the motor system 23, thereby driving its rotation, and then realizing the replacement of the scrapers 22 distributed thereon, or the adjustment of the working surface of the scraper 22. Thus, multiple scrapers can be replaced and different working surfaces of the same scraper can be adjusted without opening the warehouse.

[0061] The length of the scraper 22 is consistent with or slightly smaller than the width of the 3D printing forming cylinder. By adjusting its length, effective powder spreading can be achieved for different 3D printing devices and different printing formats. The scraper 22 itself can be a cylindrical cross-section, a triangular cross-section, a trapezoidal cross-section, a groove cross-section, or a polygonal cross-section. Different powder spreading effects can be achieved by adjusting the cross-sectional shape. For example, in a groove-shaped cross-section, powder can be stored in the middle of the groove, thereby achieving two-way powder spreading when the scraper reciprocates. The scraper 22 can be made of metal, rubber, or ceramic. If it is a cylindrical cross-section, a metal-rubber composite form can be used. In this way, the rubber part is elastic, and when there are protrusions on the printed parts, avoidance space can be provided. The metal part is more rigid, which can reduce the wear of the scraper during operation and increase its effective life.

[0062] The pressure roller mechanism 30 includes a connecting frame 31 distributed on the outside of the lateral vertical plate. A pin hole 15 is provided on the outside of the lateral vertical plate. A second fixing pin 33 is provided that passes through the first end of the connecting frame 31 and axially positions the connecting frame 31 in the pin hole 15, so that the connecting frame 31 can rotate around the second fixing pin 33.

[0063] A pressure roller 32 and a third fixing pin 34 for axially positioning the pressure roller 32 are arranged between the second ends of the connecting frame 31 , so that the pressure roller 32 can rotate around the third fixing pin 34 .

[0064] The outer side of the lateral vertical plate is provided with an up-and-down driving mechanism 13 and a connecting rod mechanism 14 driven by the up-and-down driving mechanism 13. The connecting rod mechanism 14 is connected to the connecting frame 31 and can drive the connecting frame 31 to rise or fall. The up-and-down driving mechanism 13 and the connecting rod mechanism 14 constitute the driving system.

[0065] Exemplarily, in one embodiment, the up and down driving mechanism 13 may be a telescopic motor or a telescopic cylinder or a screw mechanism, the connecting rod mechanism 14 may be a push rod or a connecting rod combination, and the connecting rod mechanism 14 is hinged to the connecting frame 31 .

[0066] Among them, the length of the pressure roller 32 is consistent with or slightly smaller than the width of the 3D printing forming cylinder. The cross-section of the pressure roller 32 is circular, and the material is a metal with a high density. Commonly used materials can be stainless steel, tungsten alloy, etc. Its main function is that after the scraper system runs to spread the powder, the pressure roller 32 adjusts the contact distance between the pressure roller and the plane on the forming substrate 50 by lifting and lowering the connecting frame 31, and applies a force to the spread powder by superimposing the pressure force of the pressure roller 32 during rolling and rotating. In this way, the spread powder is denser and the powder gap is smaller, reducing the risk of poor metallurgy during subsequent sintering and improving the density of the printed product.

[0067] The connecting frame 31 is used to provide a connection to the pressure roller 32. By controlling the up and down movement of the connecting rod mechanism 14 driven by the up and down driving mechanism 13, the up and down movement of the connecting frame 31 can be adjusted in real time, thereby driving the up and down movement of the pressure roller 32, thereby adjusting the effective distance between the pressure roller 32 and the upper surface of the forming substrate 50, thereby realizing the application of different sizes of clamping force.

[0068] The present invention Figures 1 to 6 The adjustable powder spreading structure is described in principle by taking the example of FIG. 1 as an example, but the design idea of ​​the present invention is not limited to bidirectional or circumferential powder spreading. All cases derived from the design idea and method of the present invention are the protection points of the present invention.

[0069] See also Figure 7 , the double-headed arrows indicate that the scraper system 20 can move up and down along the lifting slot 12 of the fixed bracket 10 under the action of the motor system 23 and the walking system 26.

[0070] Based on the above adjustable powder spreading structure, the present invention provides a 3D printing method:

[0071] Step S1, install the forming substrate 50 in the 3D printing device, place and fix it on the 3D printing platform. Fill the 3D printing forming chamber with powder 60, at this time, the powder 60 can be metal powder, or non-metal powder, ceramic powder, etc. Considering that conventional materials are generally metals, the present invention is described by taking metal materials as an example.

[0072] Step S2, after the metal powder is loaded, a metal scraper is used to compact the powder 60 and fill any gaps. Then, the computer operating system is controlled to make the motor system 23 and the walking system 26 of the fixed support 10 move upward along the lifting slot 12 of the fixed support to a suitable position, and then the scraper system 20 is removed from the fixed support 10 as a whole.

[0073] Step S3, select a specific scraper according to the printing material and the structural characteristics of the printed parts. For the convenience of explanation, the present invention uses a rubber and metal composite scraper with a circular cross-section. That is, the middle main body is made of metal, and the outer circumference is made of rubber material with a certain elasticity. Then the six scrapers are tightly fixed to the main turntable 21 by fixing bolts. Here, the scraper 22 and the main turntable 21 are set as a rigid whole, that is, the scraper cannot rotate around its axis. But this is only used as an example, and other operating modes have been explained above and will not be repeated here. After the scraper is installed on the main turntable, the entire scraper system is assembled, and all are 6 brand new metal and rubber composite scrapers.

[0074] Step S4, then install and fix the scraper system on the fixed bracket 10, and then control the computer operating system again so that the motor system 23 and the walking system 26 of the fixed bracket run downward to the appropriate position along the lifting groove 12 of the fixed bracket 10. Make the lower part of the scraper 22 basically fit with the upper plane of the forming substrate 50. However, a certain distance D is kept between the two, and its size is determined by the forming material powder 60, the structural characteristics of the part, the printing parameters (laser power, scanning speed, printing layer thickness, etc.). Generally speaking, D: 0~0.2mm. In this way, when the scraper 22 runs from left to right, the powder 60 can be spread on the forming substrate 50 to form a uniform powder layer with a thickness of D. At this time, the minimum distance between the scraper 22 and the upper plane of the forming substrate 50 is D, which will remain unchanged if the scraper is not worn during operation. However, during actual operation, due to the repeated friction between the scraper and the metal powder and the printed part forming layer, the value of D will gradually increase. After being ignored for a long time, the value of D will be seriously too large. As a result, the powder thickness D seriously exceeds the melting degree of the set forming sintering parameters. This leads to poor metallurgy and, in severe cases, product scrapping. Record the value D set in the computer at this time, and the computer will automatically adjust the scraper position according to this value later.

[0075] In this case, the traditional 3D printing equipment is only equipped with a single scraper, and the scraper replacement operation is complicated, so the forming chamber door can only be opened for processing. This will inevitably lead to the suspension of the continuous printing process, and a long pause will cause the continuous metallurgical process of 3D printing to be interrupted. When forming again, the formed parts and the re-formed parts are heated unevenly and misaligned, which may cause cracks in severe cases for thin-walled parts. At the same time, if the powder is spread too thickly again, it will also lead to poor metallurgy, and then form inclusions or cracks. At the same time, opening the forming chamber door will destroy the low oxygen content atmosphere of the forming chamber, and argon and other protective gases must be filled again after the scraper is replaced. The cost and time of ventilation are increased, and the pause time is further increased, which further increases the risk of deformation and cracking.

[0076] Step S5, the processed stainless steel pressure roller 32 with a smooth surface, surface roughness Ra≤3.2 and a diameter of 10-50 mm is installed on the connecting frame 31 through the third fixing pin 34. Then it is installed on the fixed bracket 10 through the second fixing pin 33 and connected to the upper and lower driving system on the side of the fixed bracket 10.

[0077] Step S6, then control the computer operating system to make the upper and lower drive systems of the fixed bracket move upward by an appropriate distance, and then drive the pressure roller to move upward by a certain distance through the connecting frame. Finally, the distance between the bottom of the pressure roller and the plane on the forming substrate 50 is equal to d, d<D, and the range of Dd is 0.01~0.05mm. Record the value d set in the computer at this time, and the computer will automatically adjust the position of the pressure roller according to this value later. In this way, the assembly and debugging of the entire adjustable powder spreading structure is completed.

[0078] Step S7, then close the 3D printing chamber, fill it with argon or other protective gas, and start heating the substrate.

[0079] Step S8, after the adjustable powder spreading structure is completely assembled and debugged, the computer operating system is controlled to make the motor system and the travel system of the fixed bracket move upward an appropriate distance T. T>D. In this way, the pressure roller and the scraper system move upward a certain distance T along the lifting groove of the fixed bracket. Then, the entire adjustable powder spreading mechanism is moved to the left side of the 3D printing device through the transmission system. After moving into place, the computer operating system automatically runs the motor system and the travel system of the fixed bracket according to the values ​​set in the previous text, so that the scraper system and the pressure roller are lowered to a specific height. Finally, the lowest points of the scraper and the pressure roller are kept at a distance of D and d from the upper surface of the forming substrate 50, respectively.

[0080] Step S9, at this time, by controlling the computer operating system, powder falls from the raw material bin (the present invention uses the raw material bin above the equipment to supply raw materials by gravity free fall as an example. The present invention can also be applied to the raw material bin below the equipment, and the raw material is supplied by lifting the barrel to send powder upward. Since this is not the focus of the present invention and the technology is very mature, it will not be described in detail here.), and falls in front of the adjustable powder spreading structure scraper 22 (because the scraper used in the example of the present invention has a circular cross-section, the powder can only be spread by pushing the scraper forward in one direction. Similarly, if a scraper with a groove-shaped cross-section is used, the powder falling from the raw material bin can fall into the grooved scraper, so that the powder can be spread in both directions. This has been explained above and will not be repeated here.).

[0081] Step S10, then manually control the computer operating system to make the entire adjustable powder spreading structure move from left to right. In this way, the scraper 22 pushes the powder 60 in front of it to spread evenly on the forming substrate 50, forming a uniform powder layer with a thickness of D. While the scraper is spreading the powder, the pressure roller behind the scraper, due to its lower height, further compacts the already spread powder 60 under the action of its own gravity. Make the powder 60 more flat and dense, so that a layer of uniform, dense and flat powder 60 with a thickness of d is left on the forming substrate 50.

[0082] Step S11, after the adjustable powder spreading structure has finished spreading powder, it moves to the right side of the 3D printing device. At this time, the computer operating system automatically controls the motor system and the walking system of the fixed bracket to move upward along the lifting groove for a certain distance T. Then, the computer operating system is manually controlled to make the entire adjustable powder spreading structure move from right to left and return to the left side of the 3D printing device described above. In this way, the adjustable powder spreading structure will not damage the flat powder spreading surface when it moves to the left.

[0083] Step S12, after the adjustable powder spreading structure moves to the left as a whole, the oxygen content in the forming chamber drops to a set appropriate value, and the substrate temperature is heated to a set appropriate value. Then the printing forming program is called. The laser emits light to start sintering the current powder spreading layer until the current layer is printed.

[0084] Step S13, during the printing of the powdered layer, the printing program is running normally. At this time, the powder feeding bin automatically feeds powder, and the entire adjustable powder spreading mechanism automatically spreads powder from left to right in the manner described above, and the pressure roller completes the powder 60 compaction operation. After the adjustable powder spreading mechanism spreads the powder, it automatically rises again, and then moves to the left to receive the powder. The laser emits light to sinter the next layer, and the cycle is repeated in sequence.

[0085] If there is no abnormality during the printing process, or the scraper is slightly worn, sintering will continue according to the established printing procedure until the printing is completed.

[0086] If the scraper is worn out, the main turntable motor system is turned on appropriately. In this way, the main turntable can rotate forward or backward around the axis at an appropriate angle, so that the circumferential surface of the scraper 22 can rotate with a certain amplitude. In this way, the complete position of the circumferential surface of the scraper 22 is adjusted to face the powder spreading side, so that the distance between it and the plane on the forming substrate 50 continues to be a constant value D. In this way, the powder spreading plane is guaranteed to be complete and uniform. Even if the working surface of the scraper is not adjusted, the pressure roller behind can compact the high points of the surface plane by gravity, thereby ensuring a certain degree of flatness.

[0087] If the scraper is severely worn, the powder spreading surface will no longer be flat even with the compaction of the pressure roller. At this time, turn on the main turntable motor system at an appropriate time, so that the main turntable can rotate forward or reverse around the axis at an appropriate angle. Then call scraper 1 or scraper 2 so that its distance from the plane on the forming substrate 50 is also guaranteed to be D. Then print normally. There is no need to pause printing at this time, when the adjustable powder spreading structure moves to the left or right. The main turntable can be controlled to rotate by manually operating the computer control system to achieve fast and efficient scraper replacement. There is no need to open the forming cabin door of the 3D printing equipment. The loss of protective gases such as argon and the long time spent on ventilation are avoided. The forming efficiency of the 3D printing equipment is greatly improved.

[0088] Furthermore, because the main turntable is equipped with multiple scrapers, when forming large-sized parts or products with large heights, the scrapers will wear out more. In this way, by rotating the main turntable, multiple scrapers can be replaced continuously without opening the warehouse or pausing. This greatly improves the forming efficiency and ensures the continuity and stability of the printing process.

[0089] Furthermore, if bidirectional powder spreading is adopted, a pressing roller mechanism is further provided on the right side of the fixed bracket, so as to ensure the compaction effect of the powder 60 during bidirectional powder spreading.

[0090] In summary, the adjustable powder spreading structure and printing method provided by the present invention have the following advantages:

[0091] The present invention provides an adjustable powder spreading structure and a 3D printing method. By introducing components such as a main turntable, a scraper system, a pressure roller mechanism, a motor system, and a walking system, the automatic adjustment of the scraper position and the rapid replacement of the scraper during the 3D printing process are realized, and the technical problems of the complicated scraper replacement operation, the need for unpacking operation, and the need for re-inflation of the forming chamber in the traditional 3D printing equipment are solved. The design improves the accuracy and uniformity of the powder spreading, ensures the continuity and stability of the printing process; the application of the pressure roller mechanism can effectively compact the powder layer, ensure the flatness and density uniformity of each layer of powder, and reduce the printing defects caused by uneven powder; the combination of the main turntable with the motor system and the walking system enables the scraper position to be accurately adjusted as needed during the printing process without pausing the equipment or opening the door, reducing the consumption of protective gas, and improving the printing efficiency and the use efficiency of the forming chamber. Through the setting of the upper and lower drive mechanisms and the connecting rod mechanism, the pressure roller mechanism and the scraper system can be quickly adjusted under different printing levels and material characteristics, adapting to a variety of printing requirements, and improving the versatility and applicability of the equipment. In addition, the design includes an exception handling strategy, which ensures printing quality and efficiency by adjusting or replacing the scraper when it is worn, further reducing equipment downtime and improving the overall performance and production efficiency of 3D printing. In short, the adjustable powder spreading structure and method of the invention significantly improves the intelligence level, forming efficiency and operation convenience of 3D printing equipment, and has high industrial application value.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An adjustable powder spreading structure, comprising L-shaped fixing brackets (10) symmetrically distributed on both sides, characterized in that: The outer side of the fixed bracket (10) is connected to a pressure roller mechanism (30) through a driving system, and the inner side of the fixed bracket (10) is provided with a scraper system (20); the fixed bracket (10) comprises a top horizontal plate and a lateral vertical plate, the top horizontal plate is provided with a bolt hole (11) fixedly connected to a moving mechanism in a 3D printing device, and the inner side of the lateral vertical plate is provided with a lifting groove (12) for vertical displacement of the scraper system (20) along the lifting groove (12); the scraper system (20) comprises a pair of main turntables (21), the inner center of the main turntable (21) is fixedly connected with a main shaft (24), a plurality of scrapers (22) arranged in a circular array are provided between the main turntables (21), and a first fixing pin (25) for axially positioning the scraper (22) is provided on the main turntable (21).

2. The adjustable powder spreading structure according to claim 1, characterized in that: A motor system (23) is arranged at the outer center of the main turntable (21), and the motor system (23) is fixedly connected to a walking system (26) that cooperates with the lifting slot (12) for vertical displacement.

3. The adjustable powder spreading structure according to claim 1, characterized in that: The pressure roller mechanism (30) comprises a connecting frame (31) distributed on the outer side of the lateral vertical plate, a pin hole (15) is arranged on the outer side of the lateral vertical plate, a second fixing pin (33) is arranged to penetrate the first end of the connecting frame (31) and axially position the connecting frame (31) in the pin hole (15), a pressure roller (32) is arranged between the second ends of the connecting frame (31), and a third fixing pin (34) is arranged to axially position the pressure roller (32).

4. The adjustable powder spreading structure according to claim 3, characterized in that: An up-and-down driving mechanism (13) and a connecting rod mechanism (14) driven by the up-and-down driving mechanism (13) are arranged on the outer side of the lateral vertical plate. The connecting rod mechanism (14) is connected to the connecting frame (31). The up-and-down driving mechanism (13) and the connecting rod mechanism (14) constitute the driving system.

5. A 3D printing method, characterized in that: The steps include: Step S1, installing a forming substrate (50) into a 3D printing device and filling a forming chamber with powder (60); Step S2, after compacting the powder (60), adjusting the scraper system (20) of the fixed support (10) to a proper position, and removing the scraper system (20); Step S3, installing the scraper (22) to the main rotating disk (21), setting the scraper (22) and the main rotating disk (21) to be rigidly connected to ensure that the scraper (22) is fixed and does not rotate; Step S4, reinstall the scraper system (20) onto the fixed bracket (10), adjust the motor system (23) and the walking system (26) to move downward along the lifting groove (12) to a suitable position, so that the lower part of the scraper (22) is in contact with the upper plane of the forming substrate (50), and adjust the position so that the scraper (22) and the forming substrate (50) maintain a predetermined distance D; Step S5, the pressure roller (32) is mounted on the connecting frame (31) 31 through the third fixing pin (34) 34, and then mounted on the fixing bracket (10) through the second fixing pin (33), and connected to the upper and lower driving systems on the side of the fixing bracket (10); Step S6, adjusting the position of the pressing roller (32) so that the distance between the bottom of the pressing roller and the forming substrate (50) is d, d<D, and the range of Dd is 0.01-0.05 mm; Step S7, closing the forming cabin door, filling with protective gas, and starting substrate heating; Step S8, adjusting the positions of the scraper (22) and the pressure roller (32), and moving the motor system (23) and the travel system (26) upward by an appropriate distance T, T>D; Step S9, dropping the powder to the front of the scraper (22) through the raw material bin; Step S10, moving the adjustable powder spreading structure, the scraper (22) spreads the powder, and the pressing roller (32) compacts the powder layer; Step S11, after the powder spreading is completed, the adjustable powder spreading structure is moved to the other side of the equipment to avoid damaging the laid powder layer; Step S12, after the oxygen content and temperature in the cabin meet the standards, laser sintering printing is started until the current layer is printed; Step S13, feeding powder and laying a second layer of powder (60), compacting the powder (60), the adjustable powder laying mechanism rises after laying the powder, then moves to the left to receive the powder, and the laser emits light to sinter the second layer of powder (60), and the cycle is repeated in sequence; Step S14, after printing is completed, cool and remove the formed parts.

6. The 3D printing method according to claim 5, characterized in that: In step S13, the following exception handling strategy is set: If there is no abnormality during the printing process, or the scraper (22) is slightly worn, sintering is continued according to the established printing procedure until the printing is completed; If the scraper (22) is worn out, the motor system (23) is started, and the main turntable (21) is rotated to adjust the position of the scraper (22), so as to ensure that the distance between the scraper (22) and the forming substrate (50) is kept at a set value D, so as to maintain the consistency and uniformity of the powder spreading surface; If the scraper (22) is severely worn and cannot ensure smooth powder spreading, continue to rotate the main turntable (21) and switch to the spare scraper (22) to ensure that the distance from the forming substrate (50) is still D. There is no need to pause printing or open the cabin door, thereby saving time and protective gas and improving printing efficiency.

7. The 3D printing method according to claim 6, characterized in that: With the fixed bracket (10) as a reference, a second pressing roller mechanism is provided which is mirror-symmetrical to the pressing roller mechanism (30).

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