Additive manufacturing powder spreading device based on soft and hard two-stage scraper switching
By using a soft/hard scraper switching device, collisions between the hard scraper and protrusions are detected and avoided, thus solving the scraper jamming problem and improving print quality and yield.
Patent Information
- Application Number
- CN202421084904.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-17
- Publication Date
- 2025-09-23
- Estimated Expiration
- 2034-05-17
AI Technical Summary
In existing technologies, soft scrapers have strong compatibility but poor forming quality, while hard scrapers are easily affected by part deformation, leading to jamming and affecting printing quality and yield.
It adopts a two-stage hard and soft scraper switching device, with the hard scraper in front and the soft scraper behind. The controller detects resistance and the vision detection system identifies protrusions to realize the lifting of the hard scraper and the switching of the soft scraper, thus avoiding the collision between the hard scraper and the protrusion.
It improved the yield rate of printed parts, avoided hard scraper jamming and equipment downtime, and ensured the continuity and quality of the printing process.
Smart Images
Figure CN223370107U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of additive manufacturing, and in particular to an additive manufacturing powder spreading device based on switching between soft and hard two-stage scrapers. Background Art
[0002] In powder bed additive manufacturing processes like selective laser melting (SLM) and electron beam melting (EBM), the powder spreading blade is a key component for ensuring print quality. Currently, two types of powder spreading blades are commonly used: soft and hard. Soft blades are highly forgiving, allowing for easier part formation and accommodating even minor local warpage. Hard blades, on the other hand, ensure superior part quality but are susceptible to part deformation. Even slight warpage can cause the blade to jam, leading to equipment downtime and resulting in scrapped parts.
[0003] Therefore, how to switch between soft and hard scrapers to improve the yield rate of printed parts has become an urgent problem to be solved. Utility Model Content
[0004] In view of the technical problems existing in the prior art of powder scraping during powder spreading printing, the present invention proposes an additive manufacturing powder spreading device based on switching between soft and hard two-stage scrapers, comprising:
[0005] A first scraper and a second scraper coupled to a scraper holder, wherein the first scraper is located in front of the second scraper in a powder scraping direction, the first scraper is a hard scraper, and the second scraper is a soft scraper, and the scraper holder is used to drive the first scraper and the second scraper to complete the powder scraping of the target plane;
[0006] a scraper switching component connected between the first scraper and the scraper holder, and configured to drive the first scraper to a first position or a second position, wherein the lower end surface of the first scraper is flush with the target plane when the first scraper is in the first position, and the lower end surface of the first scraper is higher than the target plane when the first scraper is in the second position;
[0007] The controller is electrically connected to the scraper switching component and is used to control the movement of the scraper switching component to drive the first scraper to switch to the first position or the second position.
[0008] As an optional embodiment, when the first scraper is in the first position, the lower end surface of the first scraper is flush with the lower end surface of the second scraper.
[0009] As an optional embodiment, the scraper switching component includes an electric telescopic structure, which is configured to be in an extended or shortened state according to an electrical signal, and the first end of the electric telescopic structure is connected to the first scraper, and the second end is connected to the scraper frame.
[0010] As an optional embodiment, the electric telescopic structure includes an electric telescopic rod.
[0011] As an optional embodiment, the electric telescopic structure includes an electromagnetic component, which includes a first magnet and a second magnet. The first magnet is connected to the first scraper, and the second magnet is connected to the scraper frame. The controller changes the magnetic poles of the first magnet and the second magnet through an electrical signal. When the first magnet and the second magnet repel each other, the electromagnetic component is in an extended state. When the first magnet and the second magnet attract each other, the electromagnetic component is in a shortened state.
[0012] As an optional embodiment, the scraper switching component further includes a spring, a first end of the spring is connected to the first scraper, a second end is connected to the scraper holder, and the spring is stretched when the electric telescopic structure is in an extended state.
[0013] As an optional embodiment, an elastic element is provided between the first scraper, the second scraper and the scraper frame.
[0014] As an optional embodiment, a pressure detection component is further included, which is connected to the scraper frame and is used to detect the resistance encountered by the first scraper along the powder scraping direction. The controller controls the first scraper to move from the first position to the second position according to the resistance encountered by the first scraper.
[0015] As an optional embodiment, the maximum resistance encountered by the first scraper when scraping powder is defined as Fm. When the pressure F detected by the pressure detection component is greater than 110% Fm, the controller controls the scraper switching component to move the first scraper from the first position to the second position.
[0016] As an optional embodiment, it also includes a visual detection system, which is used to obtain an image of the powder layer and identify whether there are defective areas in the image of the powder layer. The controller controls the first scraper to move from the second position to the first position according to whether there are defective areas in the image of the current powder layer.
[0017] Compared with the prior art, the advantages of the present invention are:
[0018] The powder spreading device proposed in this application is equipped with two-stage scrapers, soft and hard. During normal powder spreading, the hard scraper and the soft scraper scrape the powder with the hard scraper in front and the soft scraper in the back. When there are protrusions in the powder spreading layer, the hard scraper can be lifted by the controller, and the powder spreading layer is only scraped by the soft scraper to avoid collision between the hard scraper and the protrusions. By lifting the hard scraper, the switching between the soft and hard scrapers during powder spreading is realized to improve the yield rate of printed parts. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The accompanying drawings are not intended to be drawn to scale. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:
[0020] Figure 1 This is a structural schematic diagram of an additive manufacturing powder spreading device based on switching between soft and hard two-stage scrapers shown in the present invention. DETAILED DESCRIPTION
[0021] In order to better understand the technical content of the present invention, specific embodiments are given and described below in conjunction with the accompanying drawings.
[0022] In the additive manufacturing of metal powder by laser selective melting, the uneven temperature gradient causes residual stress in the parts, resulting in warping of the parts. The warping has a great impact on the scraping of powder by the hard scraper. Slight warping can easily cause the scraper to jam, equipment shutdown or even lead to scrapping of the part.
[0023] Therefore, it is necessary to switch between soft and hard scrapers during powder spreading. When there are no protrusions, use a hard scraper to scrape the powder. When there are protrusions, use a soft scraper to scrape the powder to avoid collision with the hard scraper and to continuously scrape the powder.
[0024] Combine Figure 1 As shown, the first aspect of the present invention proposes an additive manufacturing powder spreading device based on soft and hard two-stage scraper switching, including a first scraper 11 and a second scraper 12 coupled to a scraper holder 10, a scraper switching component 30 and a controller, and the scraper switching component 30 and the controller are electrically connected.
[0025] The first scraper 11 and the second scraper 12 are coupled to the scraper frame 10 . Along the powder scraping direction, the first scraper 11 is located in front of the second scraper 12 . The first scraper 11 is a hard scraper, and the second scraper 12 is a soft scraper.
[0026] In an optional embodiment, the softness and hardness of the hard scraper and the soft scraper are relative to the powder. Typically, the hard scraper is a hard scraper, such as a scraper made of stainless steel, cemented carbide (such as tungsten carbide, titanium carbide, etc.), or ceramic material, and the soft scraper is a soft scraper, such as rubber or other elastomers, or a soft metal material.
[0027] Furthermore, the scraper holder 10 is used to drive the first scraper 11 and the second scraper 12 to complete the scraping of powder on the target plane.
[0028] It can be understood that the scraper holder 10 can be driven by a linear drive component, such as a ball screw, etc. The scraper holder 10 is set at a specific height above the substrate. After the powder is supplied at one end of the substrate, the scraper holder 10 moves from one end of the substrate to the other end, and the scraper can form a powder layer of predetermined thickness on the surface of the substrate.
[0029] In an optional embodiment, the powder supply may be a falling powder supply or a top powder supply.
[0030] In an optional embodiment, the first scraper 11 and the second scraper 12 are each provided as one, and the scraper holder 10 scrapes the powder in a unidirectional manner.
[0031] In other embodiments, the second scraper 12 is provided as one, and the first scraper 11 is provided as two and located on both sides of the second scraper, so that the scraper holder 10 can realize bidirectional powder scraping.
[0032] Furthermore, a scraper switching component 30 is provided between the first scraper 11 and the scraper holder 10. The scraper switching component 30 is used to drive the first scraper 11 to be in a first position or a second position. When the first scraper 11 is in the first position, the lower end surface is flush with the target plane. When the first scraper 11 is in the second position, the lower end surface is higher than the target plane.
[0033] It should be understood that when the first scraper 11 is in the first position, the lower end surface of the first scraper 11 is flush with the lower end surface of the second scraper 12 .
[0034] In an optional embodiment, the scraper switching component 30 includes an electric telescopic structure, which is configured to be in an extended or shortened state according to an electrical signal, and the first end of the electric telescopic structure is connected to the first scraper 11, and the second end is connected to the scraper frame 10.
[0035] Optionally, the electric telescopic structure can be an electric telescopic rod or an electromagnetic component. For example, the electromagnetic component includes a first magnet and a second magnet. When in the extended state, the first magnet and the second magnet repel each other, and when in the shortened state, the first magnet and the second magnet attract each other. By changing the magnetic poles of the magnets, the interaction state of the first magnet and the second magnet can be changed.
[0036] In an optional embodiment, an elastic element is further provided between the electric telescopic structure and the scraper, which allows the scraper to float up and down within a certain range.
[0037] Furthermore, the scraper switching component 30 also includes a spring, a first end of the spring is connected to the first scraper 11, and a second end is connected to the scraper frame 10, and the spring is stretched when the electric telescopic structure is in an extended state.
[0038] In this way, when the first scraper 11 is in the first position, it tends to move toward the second position. Once a signal indicating that the resistance exceeds the threshold is received, the first scraper 11 can switch from the first position to the second position at a faster speed to avoid collision.
[0039] Furthermore, in order to identify protrusions on the surface of the powder layer, the resistance encountered by the first scraper 11 can be detected. In order to detect the resistance encountered by the first scraper 11 during the powder scraping process, a pressure detection component 20 is provided. The pressure detection component 20 is connected to the scraper frame 10 and is used to detect the magnitude of the resistance encountered by the first scraper 11 along the powder scraping direction.
[0040] Specifically, a pressure sensor is provided at the connection between the first scraper 11 and the scraper holder 10. When the first scraper 11 moves along the powder scraping direction, the pressure sensor can detect the pressure exerted by the first scraper 11 on the scraper holder 10 due to the powder resistance. When there is a protrusion in the powder spreading plane, once the first scraper 11 contacts the protrusion, the pressure detected by the pressure sensor increases instantaneously, and it can be determined that the first scraper 11 is in contact with the protrusion at this time.
[0041] Furthermore, when the first scraper 11 contacts the protrusion, the first scraper 11 should be immediately lifted to break away from the contact with the protrusion. When scraping powder, the first scraper 11 and the second scraper 12 are both in the target plane for scraping powder, wherein the first scraper 11 is in front to ensure that the powder is compacted, and the second scraper 12 is in the back to ensure that the smoke and dust residue generated by printing can be swept away, ensuring that the powder is clean and free of inclusions, thereby improving the printing quality. When the resistance of the first scraper 11 increases, it moves from the first position to the second position, and only the second scraper 12 is used to scrape powder, which can avoid the first scraper 11 from colliding with the protrusion.
[0042] In other embodiments, protrusions on the surface of the powder layer may be identified in other ways, such as by using a laser beam sensor.
[0043] Furthermore, after the subsequent powdering of the current powdering layer is completed by the second scraper 12, it is necessary to observe the defect status in the current powdering layer through images. Therefore, a visual inspection system 40 is set up, which is used to obtain an image of the powdering layer and identify whether there is a defective area in the image of the current powdering layer.
[0044] In an optional embodiment, the defective area appears as a black area in the image of the powder layer, which is obviously different from the normal cross-section of the part and the powder.
[0045] Furthermore, the controller is electrically connected to the pressure detection component 20, the telescopic component and the visual inspection system 40. During the process of scraping the target plane, when the pressure detected by the pressure detection component 20 exceeds the preset value, the controller controls the scraper switching component 30 to move the first scraper 11 from the first position to the second position, and the second scraper 12 completes the scraping of the target plane; and after the scraping of the current plane is completed, the controller decides whether the first scraper 11 should be restored to the first position when scraping the next layer of powder based on whether there is a defective area in the target plane identified by the visual inspection system 40.
[0046] In this way, by monitoring the resistance of the first scraper 11 when scraping powder, the scraping state of the first scraper 11 can be controlled in real time, and it can be determined when to move it from the first position to the second position. After the second scraper 12 completes spreading the powder, the image of the current powder layer can be obtained through the visual inspection system 40, and then according to whether there is a defective area in the image, it can be determined whether to reset the first scraper or continue to use the second scraper 12 to scrape the powder.
[0047] In an optional embodiment, the maximum resistance encountered by the first scraper 11 when scraping powder is defined as Fm. When the pressure F detected by the pressure detection component 20 is greater than 110% Fm, the controller controls the scraper switching component 30 to move the first scraper 11 from the first position to the second position.
[0048] In this way, the sensitivity of the first scraper 11 can be improved. When the first scraper 11 is subjected to a force exceeding 10% of the scraping resistance, the first scraper 11 moves from the first position to the second position to avoid collision with the protrusion.
[0049] In the above embodiment, when the resistance force applied to the first scraper 11 exceeds a preset value, the scraper holder 10 stops moving and moves forward again after the first scraper 11 shrinks to the second position.
[0050] Furthermore, if the defect is considered to be serious through the image of the current powder layer, continuing to use the current powder thickness to scrape the powder is not only not conducive to covering the defect, but also increases the manufacturing time. Therefore, for more serious powder layers, a thicker powder layer should be used to cover the defect as soon as possible.
[0051] Therefore, in order to change the thickness of the powder layer, the powder substrate 50 is electrically connected to the controller, and the powder substrate 50 is driven to a position with a predetermined distance from the target plane before scraping each layer of powder to determine the thickness of the current powder layer.
[0052] In an optional embodiment, the visual inspection system 40 is used to obtain the number and area of defects in the powder layer image. When the number and area of defects in the powder layer image exceed the preset value, the controller controls the movement amount of the powder substrate 50 to change the powder thickness of the next powder layer.
[0053] In this way, by obtaining the number and area of defects in the powder layer image, the degree of defects in the current powder layer image can be determined. The thickness of the powder layer can be changed according to the degree of defects to achieve a rapid transition to a height layer containing defects and increase the processing speed.
[0054] During the printing process, if the part warps and deforms, the pressure detection component 20 detects that the resistance of the first scraper 11 increases, and the first scraper 11 is immediately driven by the scraper switching component 30 to switch from the first position to the second position, and only the second scraper 12 completes the current layer of powder spreading. When the current powder spreading layer is finished, the deformation defect is confirmed by the visual inspection system 40. If there are less than 2 protrusion positions (defective areas) and the area of each is ≤5mm 2 , then keep the second scraper 12 working to see if the deformation is improved after the next layer of powder is applied; if the deformation is serious and the area is greater than 5mm 2 , the visual inspection system 40 will feed back to the controller, which will automatically adjust the powder layer thickness to twice the original one and increase the laser power to achieve the coverage transition of the printing defects; when the visual inspection system 40 confirms that the defects have been improved, the normal layer thickness and printing parameters will be restored to continue printing.
[0055] The above method can accurately identify the location and area of defects, and the raised positions can be covered with powder by switching to a soft scraper and / or increasing the thickness of the powder. At the same time, image recognition is used after each powder application to confirm whether the raised positions have disappeared. After applying powder layer by layer, the defects in the powder layer are gradually improved.
[0056] This cycle repeats until printing is completed.
[0057] In combination with the above embodiments, the powder spreading device proposed in this application is provided with two-stage scrapers, soft and hard. During normal powder spreading, the hard scraper and the soft scraper scrape the powder in the manner of the hard scraper in front and the soft scraper in the back. When there are protrusions in the powder spreading layer, the hard scraper can be lifted by the controller, and the powder spreading layer is only scraped by the soft scraper to avoid collision between the hard scraper and the protrusions. By lifting the hard scraper, the switching between the soft and hard scrapers in the powder spreading is realized to improve the yield rate of the printed parts.
[0058] While the present invention has been described above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations may be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.
Claims
1. An additive manufacturing powder spreading device based on switching between soft and hard two-stage scrapers, characterized in that: include: A first scraper (11) and a second scraper (12) coupled to a scraper holder (10), wherein the first scraper (11) is located in front of the second scraper (12) along a powder scraping direction, the first scraper (11) is a hard scraper, and the second scraper (12) is a soft scraper, and the scraper holder (10) is used to drive the first scraper (11) and the second scraper (12) to complete the powder scraping of a target plane; a scraper switching component (30) connected between the first scraper (11) and the scraper holder (10) and used to drive the first scraper (11) to be in a first position or a second position, wherein the lower end surface of the first scraper (11) is flush with the target plane when the first scraper (11) is in the first position, and the lower end surface of the first scraper (11) is higher than the target plane when the first scraper (11) is in the second position; a controller electrically connected to the scraper switching component (30) and used to control the movement of the scraper switching component (30) to drive the first scraper (11) to switch to the first position or the second position; It also includes a pressure detection component (20), the pressure detection component (20) being connected to the scraper frame (10) and being used to detect the magnitude of the resistance experienced by the first scraper (11) along the powder scraping direction, and the controller controlling the first scraper (11) to move from the first position to the second position according to the magnitude of the resistance experienced by the first scraper (11); The maximum resistance encountered by the first scraper (11) when scraping powder is defined as Fm. When the pressure F detected by the pressure detection component (20) is greater than 110% Fm, the controller controls the scraper switching component (30) to move the first scraper (11) from the first position to the second position.
2. The additive manufacturing powder spreading device based on switching between soft and hard two-stage scrapers according to claim 1 is characterized in that: When the first scraper (11) is in the first position, the lower end surface of the first scraper (11) is flush with the lower end surface of the second scraper (12).
3. The additive manufacturing powder spreading device based on switching between soft and hard two-stage scrapers according to claim 1 is characterized in that: The scraper switching component (30) comprises an electric telescopic structure, which is configured to be in an extended or shortened state according to an electrical signal, wherein a first end of the electric telescopic structure is connected to the first scraper (11), and a second end is connected to the scraper frame (10).
4. The additive manufacturing powder spreading device based on switching between soft and hard two-stage scrapers according to claim 3 is characterized in that: The electric telescopic structure includes an electric telescopic rod.
5. The additive manufacturing powder spreading device based on switching between soft and hard two-stage scrapers according to claim 3 is characterized in that: The electric telescopic structure includes an electromagnetic component, which includes a first magnet and a second magnet, wherein the first magnet is connected to the first scraper (11), and the second magnet is connected to the scraper frame (10). The controller changes the magnetic poles of the first magnet and the second magnet through an electrical signal. When the first magnet and the second magnet repel each other, the electromagnetic component is in an extended state, and when the first magnet and the second magnet attract each other, the electromagnetic component is in a shortened state.
6. The additive manufacturing powder spreading device based on switching between soft and hard two-stage scrapers according to claim 4 or 5, characterized in that: The scraper switching component (30) further comprises a spring, a first end of the spring being connected to the first scraper (11), a second end being connected to the scraper frame (10), and the spring being stretched when the electric telescopic structure is in an extended state.
7. The additive manufacturing powder spreading device based on switching between soft and hard two-stage scrapers according to claim 1 is characterized in that: An elastic element is provided between the first scraper (11), the second scraper (12) and the scraper frame (10).