Workpiece forming method for powder bed laser 3D printing and laser 3D printing apparatus

Abstract

The present application relates to the technical field of laser processing, in particular to a workpiece forming method of powder bed laser 3D printing and a laser 3D printing device, in the specific implementation, the highest point and the lowest point of the upper surface of the forming platform are obtained, and the leveling block capable of covering the highest point is formed between the focal plane and the upper surface of the forming platform, which omits the process of separately leveling the forming platform when the laser 3D printing device is used to perform laser 3D printing workpiece forming in the related art, simultaneously solves the defects of long leveling time and inability to guarantee the leveling effect when the forming platform is leveled in the related art, and achieves the purpose of guaranteeing the forming effect of the workpiece without mechanical leveling of the forming platform.

Description

Technical Field

[0001] This invention relates to the field of laser processing technology, and in particular to a workpiece forming method and laser 3D printing equipment for powder bed laser 3D printing. Background Technology

[0002] SLM additive manufacturing technology uses a laser to melt powder on a forming platform layer by layer along a preset path to form a metal entity. The specific process is as follows: the powder spreading mechanism of the equipment spreads the metal powder according to the set layer thickness, then the laser is activated for high-temperature sintering, then the forming platform descends to the set layer thickness, and the equipment repeats the powder spreading and laser sintering. This process is repeated until the printing of the entire part is completed.

[0003] Due to assembly and processing errors in the forming platform, the substrate plane generally cannot be perfectly parallel to the laser focal plane (the plane of motion of the squeegee edge) after installation. This results in uneven powder layer after the squeegee spreads the powder, directly affecting the forming quality and performance of the part in the early stages, and even causing the first layer to fail to spread powder and form. Therefore, existing SLM additive manufacturing equipment levels the forming substrate before printing to ensure uniform powder bed spreading in the early stages.

[0004] Currently, the leveling devices in SLM additive manufacturing equipment primarily achieve three-point leveling through various devices placed inside the forming platform. These leveling devices are arranged in an equilateral triangle on the forming platform, and the repeated raising and lowering of the three sets of leveling devices ensures that the forming platform remains parallel to the running plane of the powder spreading module. Leveling devices are basically divided into manual and electric leveling. Manual leveling involves manually tightening the lifting pins and clamping screws repeatedly, while electric leveling uses a motor to control the raising and lowering of the leveling devices. The ultimate leveling requirement is to ensure that the height difference between each point on the forming platform and the powder spreading scraper remains within a certain range. Height differences are typically measured using feeler gauges and dial indicators.

[0005] While related technologies can achieve the goal of leveling the forming platform, the leveling process is complex and the leveling effect cannot be guaranteed. Summary of the Invention

[0006] The main objective of this invention is to provide a workpiece forming method and laser 3D printing equipment for powder bed laser 3D printing, aiming to solve the technical problem that although related technologies can achieve the purpose of leveling the forming platform, the leveling is complex and the leveling effect cannot be guaranteed.

[0007] To achieve the above objectives, in a first aspect, the present invention proposes a workpiece forming method for powder bed laser 3D printing, wherein a forming chamber is formed on the printing equipment, and a forming platform is provided inside the forming chamber;

[0008] The powder bed laser 3D printing workpiece forming method includes the following steps:

[0009] Obtain the focal plane of the forming chamber; wherein the focal plane is located above the forming platform, and a leveling space is formed between the upper surface of the forming platform and the focal plane;

[0010] Control the forming platform to move upwards to sequentially acquire the highest and lowest points on the upper surface of the forming platform;

[0011] The forming platform is controlled to move downwards to below the focal plane, and a leveling block is formed between the upper surface of the forming platform and the focal plane; wherein the top surface of the leveling block covers the highest point, and the top surface of the leveling block coincides with the focal plane;

[0012] The powder to be formed is laid on the top surface of the leveling block to form the workpiece.

[0013] Optionally, before the step of controlling the forming platform to move upward to sequentially obtain the highest and lowest points of the forming platform, the method further includes:

[0014] A first powder is laid on the upper surface of the forming platform above the focal plane to form an initial powder layer;

[0015] The initial powder layer is scraped flat until its upper surface coincides with the focal plane to form a powder layer to be leveled.

[0016] The step of controlling the forming platform to move upward to sequentially obtain the highest and lowest points on the upper surface of the forming platform includes:

[0017] The forming platform is controlled to move upward, and the portion of the powder layer to be leveled that is above the focal plane is scraped off multiple times until the highest and lowest points are obtained in sequence.

[0018] Optionally, the step of controlling the forming platform to move upward and repeatedly scraping off the portion of the powder layer to be leveled that is above the focal plane until the highest and lowest points of the forming platform are sequentially obtained includes:

[0019] The forming platform is controlled to move upward to a target thickness so that the portion of the powder layer to be leveled that is above the focal plane forms the current layer to be scraped off, and the current layer to be scraped off is scraped off.

[0020] Return to the step of controlling the forming platform to move upward to the target thickness to form the current layer to be scraped above the focal plane, and scrape off the current layer to be scraped until the highest point is exposed;

[0021] Continue returning to the steps of controlling the forming platform to move upward to the target thickness to form the current layer to be scraped above the focal plane, and scraping the current layer to be scraped until the lowest point is exposed.

[0022] Optionally, the step of continuing to return to the step of controlling the forming platform to move upward to the target thickness to form the current layer to be scraped above the focal plane, and scraping the current layer to be scraped until the lowest point is exposed, includes:

[0023] Continue to execute the steps of controlling the forming platform to move upward to the target thickness to form the current layer to be scraped above the focal plane, and scraping the current layer to be scraped to obtain a target printing surface that coincides with the focal plane;

[0024] Detect and determine whether the first powder exists between the target printing surface and the forming platform;

[0025] When the first powder exists between the target printing surface and the forming platform, the process returns to the step of controlling the forming platform to move upward by a target thickness to form the current layer to be scraped above the focal plane, and scraping the current layer to be scraped to obtain the target printing surface that coincides with the focal plane, until there is no first powder between the target printing surface and the forming platform, so as to obtain the lowest point of the forming platform.

[0026] When there is no first powder on the target printing surface, the lowest point of the forming platform has been obtained.

[0027] Optionally, the step of controlling the forming platform to move downwards to below the focal plane and forming a leveling block between the upper surface of the forming platform and the focal plane includes:

[0028] The forming platform is controlled to move downward by a first preset thickness to form a compensation space between the focal plane and the portion of the forming platform located below the focal plane;

[0029] The powder to be formed is laid into the compensation space on the forming platform to form the current forming layer; wherein, the second powder is the raw material of the current forming layer;

[0030] The forming platform is controlled to move the current forming layer downwards by the first preset thickness, so as to form the current space between the top surface of the current forming layer and the focal plane.

[0031] The powder to be formed is laid on the current forming layer into the current space to form the target forming layer;

[0032] The target forming layer is taken as the current forming layer, and the process of controlling the forming platform to drive the current forming layer to continue moving downwards by the first preset thickness to form the current space between the top surface of the current forming layer and the focal plane is returned, until the top surface of the current forming layer covers the highest point, thus obtaining the leveling block.

[0033] Optionally, the step of spreading the powder to be formed on the top surface of the leveling block to form the workpiece includes:

[0034] The powder to be formed, having a third preset thickness, is laid on the top surface of the leveling block to form a first forming layer;

[0035] Using the top surface of the first forming layer as the first printing surface, the forming platform is controlled to move the first forming layer upward or downward to the third preset thickness, and then returns to execute the step of laying the third powder with the target thickness on the top surface of the leveling block and forming the first forming layer, until the workpiece is formed.

[0036] Based on the same technical concept, in a second aspect, the present invention also proposes a laser 3D printing device applied to the workpiece forming method of powder bed laser 3D printing described in the first aspect;

[0037] The laser 3D printing equipment includes:

[0038] A rack, wherein a placement space is formed within the rack;

[0039] A forming platform, which is vertically and retractably installed within the placement space; and,

[0040] The powder scraping mechanism includes a drive assembly, a first scraper, a second scraper, and a scraper mounting base. The drive assembly is mounted on the frame, and the mounting base is mounted on the drive assembly. The first scraper and the second scraper are rotatably mounted on the mounting base. The drive assembly can drive the mounting base to bring the first scraper and / or the second scraper closer to the forming platform and scrape off the current powder on the forming platform.

[0041] Optionally, an overflow powder bin is formed on the outer side of the forming platform within the placement space.

[0042] Optionally, at least two positioning blocks are formed in the placement space, spaced apart on the same horizontal plane, and the top surface of the positioning blocks coincides with the focal plane.

[0043] Optionally, the current powder includes powder to be leveled and powder to be shaped;

[0044] The first scraper includes a blade section connected to the mounting base and a flexible blade disposed on the blade section, the flexible blade being used to scrape off the powder to be leveled;

[0045] The second scraper is used to smooth the powder to be formed.

[0046] This invention obtains the focal plane of the forming chamber and positions it above the forming platform, creating a leveling space between the focal plane and the upper surface of the forming platform. The forming platform is then controlled to move upwards to sequentially obtain the highest and lowest points on its upper surface. Next, the forming platform is controlled to move downwards to below the focal plane, forming a leveling block between the upper surface of the forming platform and the focal plane. The top surface of the leveling block covers the highest point and coincides with the focal plane. Finally, the powder to be formed is laid on the top surface of the leveling block to form the workpiece. In practical implementation, this invention, by obtaining the highest and lowest points on the upper surface of the forming platform and forming a leveling block that covers the highest point between the focal plane and the upper surface of the forming platform, eliminates the need for separate leveling of the forming platform in related technologies when using laser 3D printing equipment to form laser 3D printed workpieces. It also solves the defects of related technologies, such as long leveling times and inability to guarantee leveling results, achieving the goal of ensuring workpiece forming results without the need for mechanical leveling of the forming platform. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0048] Figure 1 A schematic diagram showing the part of the workpiece structure that needs to be removed after the workpiece is formed using conventional techniques.

[0049] Figure 2 This is a flowchart of a workpiece forming method for powder bed laser 3D printing according to an embodiment of the present invention;

[0050] Figure 3 This is a flowchart of a workpiece forming method for powder bed laser 3D printing according to another embodiment of the present invention;

[0051] Figure 4 for Figure 3 A flowchart detailing the steps of step S200 in the example;

[0052] Figure 5 for Figure 3 A flowchart detailing the steps of step S230 in the example;

[0053] Figure 6 for Figure 2 A flowchart detailing the steps of step S300 in the example;

[0054] Figure 7 for Figure 2 A flowchart detailing the steps of step S400 in the example;

[0055] Figure 8 This is a schematic diagram of the leveling space for another embodiment of the exemplary method of the present invention;

[0056] Figure 9 for Figure 8 A schematic diagram of the powder leveling area in the example;

[0057] Figure 10 for Figure 8 A schematic diagram of the focal plane at the lowest point in the example embodiment;

[0058] Figure 11 for Figure 10 A schematic diagram of the structure of the current forming layer with the first preset thickness in the example;

[0059] Figure 12 for Figure 11 A schematic diagram of the leveling block formed after rising to a first preset thickness;

[0060] Figure 13 for Figure 12 A schematic diagram of the leveling block formed after rising two first preset thicknesses;

[0061] Figure 14 for Figure 13 A schematic diagram of the leveling block formed after rising three times the first preset thickness;

[0062] Figure 15 for Figure 14 A schematic diagram of the leveling block formed after rising to the highest point;

[0063] Figure 16 This is a side view of a laser 3D printing device according to an embodiment of the present invention;

[0064] Figure 17 for Figure 16 A schematic diagram of the planar structure of a laser 3D printing device as shown in the example;

[0065] Figure 18 for Figure 16 A schematic diagram illustrating the movement direction of the scraper mechanism;

[0066] Figure 19 This is a schematic diagram showing the position of the scraper mechanism during the workpiece forming process.

[0067] Explanation of reference numerals in the attached figures:

[0068]

[0069] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0070] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0071] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the mechanisms in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0072] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0073] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0074] The inventive concept of the present invention will be further explained below with reference to some specific embodiments.

[0075] This invention proposes a workpiece forming method and laser 3D printing equipment for powder bed laser 3D printing.

[0076] like Figures 1 to 19 As shown, an embodiment of the workpiece forming method and laser 3D printing equipment of the present invention for powder bed laser 3D printing is presented.

[0077] In this embodiment, please refer to Figures 1-15 The powder bed laser 3D printing workpiece forming method of this type includes a forming chamber formed on the printing equipment, and a forming platform set inside the forming chamber;

[0078] The workpiece forming method of powder bed laser 3D printing includes the following steps:

[0079] S100, Obtain the focal plane E of the forming chamber; wherein, the focal plane E is located above the forming platform, and a leveling space 03 is formed between the upper surface of the forming platform 100 and the focal plane E;

[0080] In related technologies, when using laser 3D printing equipment to form workpieces, an extension section or support section needs to be set on the forming platform. Laser 3D printing is then performed on the extension section or support section to achieve workpiece forming. After the workpiece is formed, the extension section or support section needs to be removed to obtain the final formed workpiece. Before forming the workpiece, the forming platform needs to be leveled to ensure the flatness of the entire formed workpiece.

[0081] Based on the example above, in this embodiment, to ensure the flatness of the formed workpiece, the forming platform needs to be adjusted. However, as mentioned earlier, related technologies that use mechanical structures to level the forming platform are not only complex but also fail to guarantee the flatness of the forming platform. Therefore, in the technology of this invention, to ensure both the flatness of the forming platform and forming efficiency, the focal plane E of the forming chamber is directly obtained before forming the workpiece.

[0082] In an exemplary embodiment, the specific process of obtaining the focal plane E is as follows:

[0083] First, move the forming platform to the lowest point of the forming chamber and stop. Then, set a focal plane E above the forming platform. It is important to note that there is no intersection between the focal plane E and the upper surface of the forming platform. That is, the upper surface of the forming platform is completely below the focal plane E.

[0084] S200: Control the forming platform to move upwards to sequentially obtain the highest and lowest points on the upper surface of the forming platform;

[0085] In this embodiment, the process of obtaining the highest and lowest points of the upper surface of the forming platform is as follows:

[0086] After obtaining the focal plane E and forming the leveling space 03 using the method described in step S100, powder is spread into the leveling space 03 on the forming platform to form the current powder layer. The current powder layer is used to obtain the highest and lowest points of the upper surface of the forming platform. After the current powder layer is laid, it is necessary to ensure that the upper surface of the current powder layer is higher than the focal plane E. Then, the leveling scraper installed on the 3D printing equipment scrapes off the part of the current powder layer that is higher than the focal plane E to form the powder layer 02 to be leveled. After obtaining the powder layer 02 to be leveled, it is necessary to ensure that the upper surface of the powder layer 02 to be leveled coincides with the focal plane E. After the leveling process is completed, the forming platform is controlled to move upward so that the top part of the powder layer 02 to be leveled is exposed and positioned above the focal plane E. The part of the powder layer 02 exposed above the focal plane E is defined as the layer to be scraped off. Next, the layer to be scraped off is scraped off using a leveling scraper so that the upper surface of the powder layer 02 after scraping coincides with the focal plane E. Then, the forming platform is controlled to move upward again to form a new layer to be scraped off with the same thickness as the layer to be scraped off. That is, the process of forming and scraping off the layer to be scraped off is repeated until the highest point of the forming platform is found. After finding the highest point, the process of forming and scraping off the layer to be scraped off is repeated until the lowest point of the forming platform is found.

[0087] It should be specifically and clearly stated that, in the process of obtaining the highest and lowest points of the forming platform, the method for determining whether the highest and lowest points have been found can be, but is not limited to, detecting whether the leveling scraper is in contact with the forming platform, detecting whether the leveling scraper is deformed, or using image recognition and comparison techniques in related technologies. For example, the blade of the leveling scraper is preferably a flexible blade. Furthermore, the process of the leveling scraper removing the layer to be scraped can be that the forming platform undergoes a continuous upward movement, and the leveling scraper continuously and reciprocates to continuously scrape the layer to be scraped; or it can be that the forming platform undergoes a progressive upward movement, and the leveling scraper scrapes the layer to be scraped once for each upward movement of the forming platform.

[0088] In a preferred embodiment, the present invention employs a progressive upward motion. The advantage of this motion method is that, during the process of obtaining the highest and lowest points of the forming platform 100, the technician can accurately record and obtain the number of movements of the forming platform and the height of each rise. Through these two data, the height of the entire leveling space 03 can be obtained, so as to control the powder to be formed during the later forming of the leveling block and the workpiece, thereby saving the powder to be formed, reducing the amount of material to be removed, and avoiding waste.

[0089] S300, control the forming platform to move downwards to below the focal plane E, and form a leveling block between the upper surface of the forming platform and the focal plane E; wherein, the top surface of the leveling block covers the highest point, and the top surface of the leveling block coincides with the focal plane E;

[0090] In this embodiment, after the highest and lowest points of the forming platform 100 are obtained sequentially, the lowest point of the forming platform 100 is located within the focal plane E, that is, please refer to... Figure 10 The lowest point coincides with the focal plane E.

[0091] Based on this, the process of forming the leveling block is as follows:

[0092] First, based on the example method described above, the number of times the forming platform rises, the corresponding rise height for each rise, the height of the leveling space 03, and the height between the highest and lowest points are obtained. Then, based on the obtained data, the number of times the forming platform 100 needs to rise and the height of each rise are determined when forming the leveling block. After determining these data, the forming platform 100 can be controlled to rise until the leveling block is formed.

[0093] It should be specifically and clearly stated that, in the exemplary technology, the leveling block can be formed in one step or after multiple progressive steps.

[0094] S400. The powder to be formed is laid on the top surface of the leveling block to form the workpiece.

[0095] In this embodiment, when spreading powder on the top surface of the leveling block, the powder spreading method can be determined based on the working parameters of the laser 3D printing equipment, the shape and specifications of the workpiece, and other data.

[0096] It should be specifically and clearly stated that, in the exemplary technology, the powder spreading method can be a single powder spreading and forming process, or multiple powder spreading processes, with each powder spreading completing a layer, and then continuing to spread powder until the entire workpiece is formed. In this embodiment, the forming stage after powder spreading is completed includes, but is not limited to, laser sintering melting forming.

[0097] The technical solution of this invention involves obtaining the focal plane E of the forming chamber and positioning it above the forming platform, forming a leveling space O3 between the focal plane E and the upper surface of the forming platform. The forming platform is then controlled to move upwards to sequentially obtain the highest and lowest points on its upper surface. Next, the forming platform is controlled to move downwards to below the focal plane E, forming a leveling block between the upper surface of the forming platform and the focal plane E. The top surface of the leveling block covers the highest point and coincides with the focal plane E. Finally, the powder to be formed is spread on the top surface of the leveling block to form the finished product. This invention, in its specific implementation, obtains the highest and lowest points on the upper surface of the forming platform and forms a leveling block between the focal plane E and the upper surface of the forming platform that covers the highest point. This eliminates the need for separate leveling of the forming platform in related technologies when using laser 3D printing equipment to form laser 3D printed workpieces. It also solves the defects of related technologies, such as long leveling time and inability to guarantee leveling effect when leveling the forming platform. This achieves the goal of ensuring the forming effect of the workpiece without mechanically leveling the forming platform.

[0098] In some specific embodiments, please refer to Figure 3 Before the step of controlling the forming platform to move upward to sequentially obtain the highest and lowest points of the forming platform, the method also includes:

[0099] A100. First powder is laid on the upper surface of the forming platform 100 above the focal plane E to form an initial powder layer;

[0100] In this embodiment, when spreading powder on the upper surface of the forming platform, the powder is mainly spread in one-time forming. That is, when spreading powder, the powder is directly spread on the forming platform, and then the leveling scraper is used to scrape the spread powder to be higher than the focal plane E to form the initial powder layer.

[0101] It should be specifically and clearly stated that, in the exemplary technology, the powder material of the initial powder layer can be the same as the material used when forming the workpiece, or it can be a different material.

[0102] A200. Scrape the initial powder layer until its upper surface coincides with the focal plane to form the powder layer to be leveled 02.

[0103] In this embodiment, when forming the powder layer to be formed, a leveling scraper is used to scrape off the portion of the initial powder layer that is higher than the focal plane E, so that the upper surface of the powder layer 02 to be leveled coincides with the focal plane E.

[0104] It should be specifically and clearly stated that, in this embodiment, the leveling scraper is preferably a flexible scraper.

[0105] In this embodiment, an initial powder layer is formed by laying a first powder layer on the forming platform 100 above the focal plane E. Then, a flexible adjusting scraper is used to scrape off the portion above the focal plane E until it coincides with the focal plane E. This eliminates the need for mechanical leveling of the forming platform 100 during implementation, improving leveling efficiency. Simultaneously, using a flexible scraper to scrape off the initial powder layer and the powder layer 02 to be leveled allows the leveling process to achieve both scraping and leveling of the powder layer 02, avoiding damage to the platform caused by the rigid scraper due to unevenness of the forming platform 100. This extends the service life of both the scraper and the forming platform 100.

[0106] The steps of controlling the forming platform to move upwards to sequentially obtain the highest and lowest points on the upper surface of the forming platform include:

[0107] Control the forming platform to move upwards and scrape off the portion of the powder layer 02 that is above the focal plane E multiple times until the highest and lowest points are obtained in sequence.

[0108] In this embodiment, by scraping the layer to be scraped multiple times, the highest and lowest points of the upper plane of the forming platform 100 are obtained sequentially. This allows the present invention to find the unevenness of the entire forming platform based on the data information obtained from the number of scraped layers and the thickness of each layer during specific implementation. This, in turn, can improve the forming accuracy of the leveling block and control the amount of powder material required for the leveling block during the subsequent forming process.

[0109] In some specific embodiments, please refer to Figure 4 The steps of controlling the forming platform to move upward and repeatedly scraping away the portion of the powder layer 02 to be leveled that is above the focal plane E until the highest and lowest points of the forming platform 100 are obtained sequentially include:

[0110] S210, control the forming platform 100 to move upward to the target thickness so that the part of the powder layer 02 to be leveled that is higher than the focal plane E forms the current layer to be scraped off, and scrape off the current layer to be scraped off;

[0111] In this embodiment, by controlling the upward movement of the forming platform 100 to the target thickness, the portion of the powder layer 02 to be leveled that is higher than the focal plane E forms the current layer to be scraped. Then, a flexible scraper is used to scrape the current layer to be scraped. This allows the present invention to precisely control the thickness of the current layer to be scraped during the process of obtaining the highest and lowest points of the upper plane of the forming platform 100. As a result, in specific implementation, the present invention can determine the specific height between the focal plane E and the lowest point of the forming platform 100 based on the thickness of the current layer to be scraped and the number of scrapings. This also allows the present invention to accurately obtain the unevenness of the forming platform 100 in specific implementation, improving the leveling accuracy when using leveling blocks for leveling.

[0112] S220, Return to the step of moving the control forming platform 100 upward to the target thickness to form the current layer to be scraped above the focal plane E, and scraping the current layer to be scraped until the highest point is exposed;

[0113] In this embodiment, a layer is scraped off with each movement, and the movement height is the same each time, so that the distance between the focal plane E and the highest point of the forming platform 100 can be accurately obtained in the specific implementation of the present invention.

[0114] S230, Continue to return to the step of moving the control forming platform 100 upward to the target thickness to form the current layer to be scraped above the focal plane E, and scrape off the current layer to be scraped until the lowest point is exposed.

[0115] In this embodiment, a layer is scraped off with each movement, and the movement height is the same each time, so that the distance between the highest point and the lowest point of the forming platform 100 can be accurately obtained in the specific implementation of the present invention.

[0116] In this embodiment, by repeatedly scraping away the current layer to be scraped with the same thickness, the present invention can sequentially obtain the distances between the focal plane E and the highest point of the forming platform 100, as well as between the highest and lowest points of the forming platform 100. This allows the present invention to determine the specific height of the leveling block based on the obtained distances, ensuring the leveling efficiency of the entire leveling process. Simultaneously, by controlling the height of the leveling block, the present invention can ensure the control of the amount of forming powder used, avoiding waste.

[0117] In some specific embodiments, please refer to Figure 5 The process continues by returning to the step of controlling the forming platform 100 to move upwards to the target thickness to form the current layer to be scraped above the focal plane E, and scraping the current layer to be scraped until the lowest point is exposed, including:

[0118] S231. Continue to return to the step of controlling the forming platform 100 to move upward to the target thickness to form the current layer to be scraped above the focal plane E, and scrape off the current layer to be scraped to obtain a target printing surface that coincides with the focal plane E.

[0119] In this embodiment, after obtaining the highest point of the forming platform 100 and during the process of obtaining the lowest point of the forming platform 100, the surface that coincides with the focal plane E after scraping off a layer of the current scraped layer is taken as the target printing surface. This allows the present invention to determine whether there is still first powder on the forming platform 100 based on the target printing surface, thus avoiding the defect of not being able to determine whether there is still unscraped powder on the upper surface of the forming platform 100.

[0120] S232. Detect and determine whether there is first powder between the target printing surface and the forming platform;

[0121] In this embodiment, when determining whether there is still first powder between the target printing surface and the forming platform 100, the specific determination method includes, but is not limited to, taking a picture of the target printing surface with a high-definition camera, and then using existing image recognition and other technologies to analyze the color differences in the high-definition picture.

[0122] It should be specifically and clearly stated that, in the exemplary embodiment, the technology for determining whether there is first powder between the target printing surface and the forming platform 100 is prior art. In this embodiment, it is only applied without involving specific judgment methods or improvements or designs to the judgment distance. Therefore, it will not be described in detail here. However, it can be exemplified that the judgment methods exemplified in this embodiment include, but are not limited to, the following types: judgment using image methods, judgment using laser scanning methods, etc.

[0123] S233. When there is first powder between the target printing surface and the forming platform, return to execute the step of controlling the forming platform 100 to move upward by a target thickness to form the current layer to be scraped above the focal plane E, and scrape the current layer to be scraped to obtain the target printing surface that coincides with the focal plane, until there is no first powder between the top surface of the current forming layer and the forming platform, so as to obtain the lowest point of the forming platform.

[0124] In this embodiment, when there is first powder between the target printing surface and the forming platform 100, it indicates that the lowest point of the forming platform 100 has not yet appeared, and it is necessary to continue or reach the lowest point. Since the specific height between the highest and lowest points of the upper plane of the forming platform 100 is unknown before implementation, the method of judging after each layer is scraped can be adopted during the process of obtaining the lowest point. In this way, the invention can quickly record the number of scrapings during the process of obtaining the lowest point of the forming platform 100 to avoid the defect of inaccurate or non-judgment of the specific height between the highest and lowest points of the forming platform 100 due to multiple scrapings and no judgment after each scraping. At the same time, it also ensures the efficiency of obtaining the lowest point during implementation.

[0125] S234. When there is no first powder on the target printing surface, the lowest point of the forming platform has been obtained.

[0126] In this embodiment, by determining whether there is first powder between the target printing surface and the forming platform 100, the present invention can effectively ensure the efficiency and accuracy of obtaining the lowest point of the forming platform 100 during specific implementation.

[0127] In some specific embodiments, please refer to Figure 6 The step of controlling the forming platform to move downwards to below the focal plane E and forming a leveling block between the upper surface of the forming platform and the focal plane E includes:

[0128] S310, Control the forming platform to move downward by a first preset thickness to form a compensation space 04 between the focal plane E and the portion of the forming platform located below the focal plane E;

[0129] In this embodiment, by controlling the forming platform to move downward by a first preset thickness, the present invention can obtain the specific descent height of the forming platform 100 based on the previously obtained data after obtaining the highest and lowest points of the forming platform 100. At the same time, the present invention can determine the specific height of the leveling block and the specific cutting thickness after the workpiece is formed based on this height during specific implementation.

[0130] It should be specifically and clearly stated that, in this embodiment, the first preset thickness is preferably the thickness when one layer of the leveling block is formed during the forming process. For example, if the thickness of the leveling block is 1 cm, and it takes 100 forming cycles to form the leveling block, then the first preset thickness is 0.01 mm.

[0131] S320. The powder to be formed is laid in the compensation space 04 on the forming platform to form the current forming layer 05; wherein, the second powder is the raw material of the current forming layer 05.

[0132] In this embodiment, by laying the powder to be formed in the compensation space 04 and then forming the current forming layer 05 by means of laser sintering and melting, the present invention can control the forming accuracy of the leveling block in specific implementation.

[0133] S330, Control the forming platform to drive the current forming layer 05 to continue moving downward by a first preset thickness, so as to form the current space between the top surface of the current forming layer 05 and the focal plane E;

[0134] In this embodiment, by controlling the forming platform 100 to drive the current forming layer 05 to continue moving downwards to a first preset thickness to form the current space, the present invention can use the upper surface of the current forming layer 05 as the forming surface in specific implementation, thus realizing the function of continuous forming.

[0135] S340. Lay the powder to be formed onto the current space on the current forming layer 05 to form the target forming layer;

[0136] In this embodiment, by laying the powder to be formed on the current forming layer 05 and forming the target forming layer, the present invention can realize the continuous forming function of the leveling block in specific implementation.

[0137] S350, Take the target forming layer as the current forming layer 05, and return to execute the step of controlling the forming platform to drive the current forming layer 05 to continue moving downwards to a first preset thickness, so as to form the current space between the top surface of the current forming layer 05 and the focal plane E, until the current surface to be printed covers the highest point, and a leveling block is obtained.

[0138] In this embodiment, by forming the leveling block multiple times and in a cyclic manner, the present invention can effectively solve the defects in the related technology that result in poor forming effect of the leveling block due to one-time forming or discontinuous forming.

[0139] In some specific embodiments, please refer to Figure 7 The step of spreading the powder to be formed on the top surface of the leveling block to form the workpiece includes:

[0140] S410. A powder to be formed with a third preset thickness is laid on the top surface of the leveling block to form a first forming layer.

[0141] In this embodiment, by laying a powder of a third preset thickness on the top surface of the leveling block and sintering and melting it into a first forming layer, the present invention can quickly form a workpiece in specific implementation.

[0142] It should be specifically and clearly stated that, in the exemplary technology, when spreading powder on the workpiece, the leveling scraper used for leveling needs to be replaced with a forming scraper. In the exemplary technology, the forming scraper is preferably a rigid scraper. Of course, to ensure forming efficiency, in the exemplary technology of this invention, the forming scraper and the leveling scraper can be installed simultaneously on the same scraper mounting base 230. The scraper mounting base 230 adopts a vertically rotating mounting method. In this way, the present invention can achieve the functions of leveling and forming in specific implementation. Furthermore, in this embodiment, the forming method of the first forming layer is the same as the forming method of the leveling block, and will not be described in detail here.

[0143] S420. Using the top surface of the first forming layer as the first printing surface, control the forming platform to drive the first forming layer to move upward or downward to a third preset thickness, and return to execute the step of laying the third powder with the target thickness on the top surface of the leveling block and forming the first forming layer, until the workpiece is formed.

[0144] In this embodiment, by forming the first forming layer multiple times and sequentially, the present invention can precisely control the forming accuracy and forming effect of the workpiece during specific implementation.

[0145] Based on the same technical concept, please refer to Figures 16 to 19 The present invention also proposes a laser 3D printing device, which is applied to the powder bed laser 3D printing workpiece forming method of the first aspect;

[0146] The laser 3D printing equipment includes a frame 300, a forming platform, and a powder scraping mechanism 200. A placement space 01 is formed within the frame 300. The forming platform is vertically and flexibly installed within the placement space 01. The powder scraping mechanism 200 includes a drive assembly 240, a first scraper 210, a second scraper 220, and a scraper mounting base 230. The drive assembly 240 is mounted on the frame 300, and the mounting base 230 is mounted on the drive assembly 240. The first scraper 210 and the second scraper 220 are rotatably mounted on the mounting base 230. The drive assembly 240 can drive the mounting base 230 to bring the first scraper 210 and / or the second scraper 220 closer to the forming platform and scrape off the current powder on the forming platform.

[0147] In this embodiment, a frame 300 is set up, and a forming platform 100 is set up in the placement space 01 within the frame 300. At the same time, a scraping mechanism 200 installed in the placement space 01 is set up above the forming platform. When the present invention is implemented, a focal plane E is formed in the space between the scraping mechanism and the forming platform 100. Then, by controlling the distance between the focal plane E and the forming platform 100, a leveling space 03 and a compensation space 04 are formed in the placement space 01. At the same time, the first scraper 210 in the scraping mechanism realizes the leveling function of the leveling space 03. After leveling, the second scraper 220 is used to form the workpiece on the leveling block. This enables the present invention to quickly level the forming platform 100 when it is implemented, which solves the technical defects of the related technology that require mechanical leveling of the forming platform, resulting in uncontrollable leveling accuracy and poor leveling efficiency.

[0148] It should be specifically and clearly stated that, in the exemplary technology, the first scraper 210 is a flexible scraper, and the second scraper 220 is a rigid scraper. Furthermore, in this embodiment, only the parts that are improvements and inventions related to the present invention are described. Other mechanisms or devices of the laser 3D printing equipment have not been improved in this embodiment; therefore, the parts of the laser 3D printing equipment that have not been improved or designed by the present invention will not be described in detail in this embodiment.

[0149] In some specific embodiments, please refer to Figure 17 An overflow powder bin 700 is formed on the outside of the forming platform and is located in the placement space 01.

[0150] In this embodiment, by forming an overflow powder bin 700 in the placement space 01 on the outside of the forming platform, the present invention can collect the powder that needs to be scraped off during the leveling process, thereby realizing the secondary application of the powder and avoiding waste.

[0151] In some specific embodiments, please refer to Figure 19 At least two positioning blocks 400 are formed in the placement space 01, spaced apart on the same horizontal plane, with the top surface of the positioning block 400 coinciding with the focal plane E.

[0152] In this embodiment, by setting at least two positioning blocks 400 located on the same horizontal plane, and making the top surface of the positioning blocks 400 coincide with the focal plane E, the present invention can locate and control the position of the focal plane E in specific implementation.

[0153] It should be specifically and clearly stated that, in the exemplary technology, the positioning block 400 can be installed in the placement space 01 of the frame 300 by means of welding, integral forming with the frame 300, threaded connection, or other methods that can be directly fixed. That is, it can ensure that the focal plane E is always in a preset position. Of course, the positioning block 400 can be detachably or slidably installed in the placement space 01 by means of synchronous or separate height adjustment. The specific method used can be selected and determined by those skilled in the art according to actual needs.

[0154] In some specific embodiments, please refer to Figure 18 The current powder includes powder to be leveled and powder to be shaped; the first scraper 210 includes a blade section connected to the mounting base 230 and a flexible blade on the blade section, the flexible blade being used to scrape off the powder to be leveled; the second scraper 220 is used to level the powder to be shaped.

[0155] In this embodiment, by using the first scraper 210 for leveling and the second scraper 220 for shaping, the present invention can solve the defects in related technologies where the scraper and the platform are easily damaged due to the unevenness of the forming platform 100 when using a rigid scraper for leveling.

[0156] In some specific embodiments, the methods and apparatus of the present invention may also be implemented using the following examples:

[0157] The mechanical leveling device of the forming platform 100 is eliminated, and the leveling of the forming platform 100 is achieved directly by alternating the leveling scraper and the forming scraper of the powder spreading module;

[0158] The leveling principle is to achieve regional differences in powder thickness by utilizing the vertical deformability of the leveling scraper and the characteristic that the support section or extension section (wire cutting area) of the printed part does not affect the final size of the shaped part, thereby gradually compensating for the height difference between the forming platform 100 and the laser focal plane E.

[0159] Advantages:

[0160] The forming platform 100 has no internal mechanical leveling device, and all surfaces of the forming platform 100 are in contact, with the load evenly distributed.

[0161] There is no need to repeatedly measure height differences and adjust lifting and leveling devices, making the leveling process simpler;

[0162] Suitable for large-format additive printing equipment.

[0163] The leveling process is easy to automate.

[0164] The formed parts printed by SLM are divided into extension sections and part sections. The extension section is the connection area between the forming platform 100 and the formed part, which reserves the allowance for cutting the part and has a certain height. The part section is the formed part obtained after wire cutting. The good performance of the formed part depends on the overlap of the laser focal plane E and the powder-spreading surface. The powder-spreading surface is usually determined by the straightness and horizontality of the lower edge of the squeegee. Therefore, by adjusting the lower edge of the squeegee to overlap with the laser focal plane E, the overlap between the focal plane E and the powder-spreading surface can be effectively guaranteed.

[0165] After the shaped part is printed, it will be cut from the forming platform 100 by a wire cutting device. The part lost during the cutting is the height of the extension section, which does not affect the size of the final shaped part.

[0166] In this case, the characteristic that the extension section does not affect the final size of the molded part is fully utilized, and the height compensation amount for powder leveling is designed in the extension section of the molded part.

[0167] Powder spreading module: mainly includes a scraper holder, leveling scraper, forming scraper, rotating mechanism, etc. The leveling scraper and forming scraper are respectively installed on both sides of the scraper holder;

[0168] Leveling scraper: A plastic scraper with a certain amount of deformation or a specially designed scraper with a high degree of extension is used to compensate for the height difference of the leveling and forming platform 100 during the initial powder spreading. The compensation dimension is located in the extension section of the printed part.

[0169] Forming scraper: It is consistent with the existing scrapers in the current equipment. Different materials of scrapers can be selected according to different printed parts. It is used as the powder spreading scraper after the forming platform 100 has completed powder spreading compensation and leveling, and the part printing begins.

[0170] Rotating mechanism: Built into the powder spreading module, it realizes the direction adjustment of the leveling scraper and the forming scraper by rotating the scraper holder;

[0171] Guide rail: The guide rail enables the reciprocating toner spreading motion of the toner spreading module. The direction of travel of the guide rail is parallel to the top and bottom of the printing chamber.

[0172] Height positioning block 400: The printing chamber bottom plate is pre-installed between the front toner overflow chamber 700 and the chamber door. The upper surface of the positioning block 400 coincides with the laser focal plane E. The scraper is placed on the positioning block 400 and installed on the scraper holder, ensuring that the lower surface of the scraper coincides with the laser focal plane E.

[0173] Laser focal plane E: The position of focal plane E can be determined during optical module calibration;

[0174] Real-time monitoring module: The high-definition camera monitors the entire printing area, monitors the printing process in real time, captures and uploads images of the printing area, and analyzes the powder spreading quality and forming quality through image recognition;

[0175] The vision processing module monitors the powder bed image fed back by the camera 600, processes the data, and intelligently judges the quality of the powder spreading image to determine the timing for powder spreading, leveling, and scraper rotation. In this exemplary technology... Figure 16 The cone-shaped dashed area in the diagram represents the monitoring range of the monitoring camera 600 in this embodiment.

[0176] Before the actual printing, the leveling squeegee and the forming squeegee are installed on both sides of the powder spreading module, and the height is positioned by the squeegee positioning block 400 pre-installed in the printing chamber to ensure that the lower surface of the squeegee coincides with the laser focal plane E.

[0177] The leveling scraper is rotated downwards by the scraper rotation device built into the powder spreading module, that is, the leveling scraper is facing the forming platform 100. Since the leveling scraper has a certain amount of deformation, when there are height differences in various parts of the forming platform 100, dynamic compensation can be achieved through deformation.

[0178] When the forming platform 100 is raised to a height of around the positioning block 400, there is a height difference between the forming plane and the theoretical focal plane E at various points, which needs to be compensated and leveled by the powder spreading module during printing.

[0179] The powder spreading quality judgment module (real-time monitoring module and vision processing module) is activated to identify the powder spreading quality online, and then the lifting and lowering of the forming platform 100 is controlled.

[0180] Assuming the maximum height difference h of the forming platform 100, the forming platform 100 is raised to near the height of the positioning block 400. Powder is laid by a leveling scraper. The powder laying quality judgment module monitors and analyzes the powder coverage of the forming platform 100. If it is determined that the powder is too thick, the forming platform 100 is raised to ensure that the lowest surface of the forming platform 100 is not covered by powder. At this time, the lowest point of the forming platform 100 is at the laser focal plane E, and the reference surface for powder laying and leveling is determined.

[0181] After determining the leveling reference plane, control the forming platform 100 to descend by one layer thickness n, lay the first layer of powder with the leveling scraper and laser sinter it. At this time, the lowest point of the forming plane is filled by a single layer of solid, and the leveling height becomes hn.

[0182] Continue to control the forming platform 100 to descend by another layer thickness n, lay powder and laser sinter, and wait for the leveling height to become h-2n;

[0183] By analogy, until the total powder layer thickness N≥h during the leveling period, the powder quality judgment module can determine that the entire surface has been uniformly powdered, and the leveling height is completely compensated by the powder sintering of the leveling scraper, and the height difference of the entire surface of the forming platform 100 is completely eliminated.

[0184] After the powder is spread and leveled, rotate the scraper holder using the rotating device of the powder spreading unit to replace the leveling scraper with the forming scraper, and then start the normal printing process.

[0185] The technical solution of this invention involves obtaining the focal plane E of the forming chamber and positioning it above the forming platform, forming a leveling space O3 between the focal plane E and the upper surface of the forming platform. The forming platform is then controlled to move upwards to sequentially obtain the highest and lowest points on its upper surface. Next, the forming platform is controlled to move downwards to below the focal plane E, forming a leveling block between the upper surface of the forming platform and the focal plane E. The top surface of the leveling block covers the highest point and coincides with the focal plane E. Finally, the powder to be formed is spread on the top surface of the leveling block to form the finished product. This invention, in its specific implementation, obtains the highest and lowest points on the upper surface of the forming platform and forms a leveling block between the focal plane E and the upper surface of the forming platform that covers the highest point. This eliminates the need for separate leveling of the forming platform in related technologies when using laser 3D printing equipment to form laser 3D printed workpieces. It also solves the defects of related technologies, such as long leveling time and inability to guarantee leveling effect when leveling the forming platform. This achieves the goal of ensuring the forming effect of the workpiece without mechanically leveling the forming platform.

[0186] The above description is merely an optional embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for forming a workpiece using powder bed laser 3D printing, characterized in that, The method is applied to a laser 3D printing equipment, which has a forming chamber and a forming platform inside the forming chamber. The powder bed laser 3D printing workpiece forming method includes the following steps: Obtain the focal plane corresponding to the forming platform in the forming chamber; wherein the focal plane is located above the forming platform, and a leveling space is formed between the upper surface of the forming platform and the focal plane; Control the forming platform to move upwards to sequentially acquire the highest and lowest points on the upper surface of the forming platform; The forming platform is controlled to move downward by a first preset thickness to create a compensation space between the focal plane and the portion of the forming platform located below the focal plane. A second powder is laid into the compensation space on the forming platform to form the current forming layer; wherein the second powder is the raw material of the current forming layer. The forming platform is controlled to move the current forming layer downwards by the first preset thickness, so as to form the current space between the top surface of the current forming layer and the focal plane: The powder to be formed is laid on the current forming layer into the current space to form the target forming layer; The target forming layer is taken as the current forming layer, and the process of controlling the forming platform to drive the current forming layer to continue moving downward by the first preset thickness to form the current space between the top surface of the current forming layer and the focal plane is returned to the execution step until the top surface of the current forming layer covers the highest point, thus obtaining the leveling block; The powder to be formed, having a third preset thickness, is laid on the top surface of the leveling block to form a first forming layer: Using the top surface of the first forming layer as the first printing surface, the forming platform is controlled to move the first forming layer upward or downward to the third preset thickness, and then returns to the step of laying the powder to be formed with the third preset thickness on the top surface of the leveling block and forming the first forming layer, until the workpiece is formed.

2. The workpiece forming method of powder bed laser 3D printing as described in claim 1, characterized in that, Before the step of controlling the forming platform to move upward to sequentially obtain the highest and lowest points of the forming platform, the method further includes: A first powder is laid on the upper surface of the forming platform above the focal plane to form an initial powder layer; The initial powder layer is scraped flat until its upper surface coincides with the focal plane to form a powder layer to be leveled. The step of controlling the forming platform to move upward to sequentially obtain the highest and lowest points on the upper surface of the forming platform includes: The forming platform is controlled to move upward, and the portion of the powder layer to be leveled that is above the focal plane is scraped off multiple times until the highest point and the lowest point are obtained in sequence.

3. The workpiece forming method of powder bed laser 3D printing as described in claim 2, characterized in that, The step of controlling the forming platform to move upward and repeatedly scraping off the portion of the powder layer to be leveled that is above the focal plane until the highest and lowest points of the forming platform are sequentially obtained includes: The forming platform is controlled to move upward to a target thickness so that the portion of the powder layer to be leveled that is above the focal plane forms the current layer to be scraped off, and the current layer to be scraped off is scraped off. Return to the step of controlling the forming platform to move upward to the target thickness to form the current layer to be scraped above the focal plane, and scrape the current layer to be scraped until the highest point is exposed; Continue to perform the steps of controlling the forming platform to move upward to the target thickness to form the current layer to be scraped above the focal plane, and scraping the current layer to be scraped until the lowest point is exposed.

4. The workpiece forming method of powder bed laser 3D printing as described in claim 3, characterized in that, The step of continuing to return to the step of controlling the forming platform to move upward to the target thickness to form the current layer to be scraped above the focal plane, and scraping the current layer to be scraped until the lowest point is exposed, includes: Continue to execute the steps of controlling the forming platform to move upward to the target thickness to form the current layer to be scraped above the focal plane, and scraping the current layer to be scraped to obtain a target printing surface that coincides with the focal plane; The system detects and determines whether the first powder exists between the target printing surface and the forming platform. When the first powder exists between the target printing surface and the forming platform, it returns to the step of controlling the forming platform to move upward by a target thickness to form the current layer to be scraped above the focal plane and scraping the current layer to be scraped to obtain a target printing surface that coincides with the focal plane, until the first powder does not exist between the target printing surface and the forming platform, so as to obtain the lowest point of the forming platform. When the first powder is not present on the target printing surface, the lowest point of the forming platform has been obtained.

5. A laser 3D printing device, characterized in that, The workpiece forming method applied to powder bed laser 3D printing as described in any one of claims 1 to 4: The laser 3D printing equipment includes: The rack, within which a placement space is formed: A forming platform, wherein the forming platform is vertically and retractably installed within the placement space; and, The powder scraping mechanism includes a drive assembly, a first scraper, a second scraper, and a scraper mounting base. The drive assembly is mounted on the frame, and the mounting base is mounted on the drive assembly. The first scraper and the second scraper are rotatably mounted on the mounting base. The drive assembly can drive the mounting base to bring the first scraper and / or the second scraper closer to the forming platform and scrape off the current powder on the forming platform.

6. The laser 3D printing equipment as described in claim 5, characterized in that, An overflow powder bin is formed on the outer side of the forming platform within the placement space.

7. The laser 3D printing equipment as described in claim 5, characterized in that, The placement space contains at least two positioning blocks spaced apart on the same horizontal plane, with the top surface of the positioning blocks coinciding with the focal plane.

8. The laser 3D printing equipment as described in any one of claims 5 to 7, characterized in that, The current powder includes powder to be leveled and powder to be shaped: The first scraper includes a blade section connected to the mounting base and a flexible blade disposed on the blade section, the flexible blade being used to scrape off the powder to be leveled. The second scraper is used to smooth the powder to be formed.

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