Additive manufacturing printing method and scraper device to prevent scraper deformation

Abstract

This invention discloses an additive manufacturing printing method and its scraper device to prevent scraper deformation. The scraper device is characterized by maintaining its stability during powder spreading. When the scraper encounters an abnormal protrusion, it transmits a pressure signal to a pressure detection device. After powder spreading in the current layer is completed, the scraper performs the following actions: the scraper braking system is released, and the drive mechanism rotates the scraper, displacing the scraper point that was squeezed and rubbed by the abnormal protrusion to a non-working position; then, the scraper remains stable and continues spreading powder. Simultaneously, the information acquisition system records the abnormal protrusion position information, and the computer, based on the scraper movement time, distance, and pressure feedback from the pressure detection device, obtains the position of the abnormal protrusion in the current layer. This not only protects the scraper but also avoids wasting the printed workpiece by interrupting the process; it can provide real-time feedback on abnormal point information and automatically modify parameters, causing the protrusion to stop growing or even gradually disappear.

Description

Technical Field

[0001] This invention relates to additive manufacturing printing technology, and in particular to an additive manufacturing printing method and a scraper device for preventing scraper deformation. Background Technology

[0002] In the process of powder-spreading laser additive manufacturing of metal parts, the designed 3D model of the part is layered and sliced ​​according to the printing thickness. Each layer is scanned and powder-spreading action is required. Due to differences in the shape and structure of the part or unreasonable process settings, such as uneven heating of the powder, excessive local heat, or other reasons, abnormal protrusions may occur during the forming process, damaging the powder-spreading squeegee and causing defects in the powder bed during subsequent powder-spreading processes, affecting the overall quality of the part, or even scrapping it.

[0003] All publicly available additive manufacturing printing blades are either fixed or rotary. For example, patent publication number CN115507809B discloses a blade deformation monitoring system, additive manufacturing printing equipment, and method. This system embeds a detection mechanism (i.e., a limit protector) and a pressure sensor within the blade of the additive manufacturing printing equipment. By monitoring damage and / or deformation of the blade during its movement, it achieves real-time detection of blade damage and detects deformation caused by impacts encountered during powder spreading and deformation due to part warping, thereby controlling the powder spreading and printing processes.

[0004] For example, a novel scraper device and powder spreading method for additive manufacturing is disclosed in patent publication number CN114603849A. The device includes a scraper mounting shaft bracket, a scraper mounting shaft, a plurality of flexible scrapers, and a scraper mounting shaft rotation drive device. The scraper mounting shaft is mounted on the scraper mounting shaft bracket, the plurality of flexible scrapers are mounted on the scraper mounting shaft, and the scraper mounting shaft rotation drive device is used to drive the scraper mounting shaft to rotate.

[0005] When the printing time in laser additive manufacturing of metal parts is long, existing technologies generally require dedicated personnel to be stationed next to the equipment continuously to prevent part deformation during printing, which could lead to part scrapping and equipment damage. However, the 3D printers in the aforementioned disclosed technologies employ monitoring and passive tool changing methods to avoid the impact of worn or damaged scrapers on the product. Since these scrapers are fixed during printing, they cannot automatically avoid abnormal protrusions. If not handled promptly, these scrapers are easily damaged, leading to printing failure. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems and provide an additive manufacturing printing method and its squeegee device for preventing squeegee deformation. It has the characteristics of instantly detecting abnormalities such as protrusions and promptly feeding them back to the control system, actively moving the squeegee strip to the impact point to avoid printing being abandoned halfway, and preventing damage to the squeegee caused by repeated friction of the protrusions against the same position of the squeegee strip.

[0007] The above-mentioned technical problem of the present invention is mainly solved by the following technical solution: an additive manufacturing printing method for preventing squeegee deformation, characterized in that, when the squeegee moves to spread powder, the squeegee is kept stable; when the squeegee encounters an abnormal protrusion, the squeegee transmits a pressure signal to the pressure detection device; after the powder is spread in the current layer, the squeegee performs the following actions: the squeegee braking system is released, and the drive mechanism drives the squeegee to rotate, causing the squeegee point squeezed and rubbed by the abnormal protrusion to be displaced to a non-working position; at this time, the squeegee is kept stable and continues to move to spread powder; at the same time, the information acquisition system records the abnormal protrusion position information, and the computer obtains the position of the abnormal protrusion in the current layer based on the squeegee movement time, distance, and pressure point feedback from the pressure detection device.

[0008] In the aforementioned additive manufacturing printing method for preventing squeegee deformation, preferably, the squeegee is a flexible squeegee strip, and the squeegee strip is a rotating belt composed of a set of wheels.

[0009] In the aforementioned additive manufacturing printing method for preventing scraper deformation, preferably, the scraper braking system includes a drive mechanism for rotating the scraper and a clamping device on the side of the scraper.

[0010] In the aforementioned additive manufacturing printing method for preventing scraper deformation, preferably, the non-working point is the non-contact portion of the scraper outside the normal working length of the printer forming platform.

[0011] A scraper device for an additive manufacturing printing method to prevent scraper deformation includes a forming housing, a forming platform located inside the forming housing, and a scraper mechanism cooperating with the forming platform. The scraper mechanism is characterized by having a scraper at its bottom end, the scraper being a flexible scraper strip positioned on two drive wheels, each drive wheel positioned on a rotating shaft mounted on a scraper holder. A fixing post is provided between the two rotating shafts, and an electromagnet is mounted on the fixing post. A braking cover plate is provided on the outside of the scraper, cooperating with both the side of the scraper and the fixing post.

[0012] In the aforementioned additive manufacturing squeegee device for preventing squeegee deformation, preferably, a pressure detection device is provided on the squeegee holder body, and the pressure detection device is located on the side of a working length section below the rotating strip squeegee.

[0013] In the aforementioned additive manufacturing squeegee device for preventing squeegee deformation, preferably, the rotating shaft includes a first rotating shaft and a second rotating shaft, the drive wheel includes a first drive wheel and a second drive wheel, and the drive wheel is provided with a squeegee groove.

[0014] In the aforementioned additive manufacturing squeegee device for preventing squeegee deformation, preferably, the fixing post is provided in several places, the end of the fixing post is provided with an electromagnet, and the brake cover is provided with a guide sleeve that cooperates with the fixing post, the bottom end of the guide sleeve being a magnetic body that cooperates with the electromagnet.

[0015] In the aforementioned additive manufacturing squeegee device for preventing squeegee deformation, preferably, the pressure detection device covers a length greater than or equal to the working length of the squeegee.

[0016] In the aforementioned additive manufacturing squeegee device for preventing squeegee deformation, preferably, the width of the brake cover is greater than or equal to the width of the rotating strip squeegee.

[0017] This technical solution is specifically designed to address the phenomenon of abnormal protrusions in the production of metal parts using laser additive manufacturing with powder spread. It still employs a flexible squeegee, but is designed as a rotating belt structure consisting of a set of pulleys. During normal printing, the squeegee moves to spread powder, maintaining its stability. However, when the squeegee encounters a protrusion, the squeegee itself, under the action of additional resistance, transmits a pressure signal to the pressure detection device at the set position, indicating the presence of an abnormal protrusion. Therefore, after the current layer of powder spread is completed, the control system releases the brake on the squeegee, and the drive mechanism rotates the squeegee to change its working position, displacing the point that was squeezed and rubbed by the protrusion to a non-working position, while the current printing operation continues.

[0018] The scraper section moved to a non-working position is identified by the information acquisition system and computer based on its movement time, distance, and pressure point feedback from the pressure detection device, allowing the computer to determine the location of any abnormal protrusions in the current layer. Once the location of the abnormal protrusion is known, further processing can be performed, such as adding powder to the abnormal protrusion, modifying the filling parameters of the next layer slice, adjusting the power and speed of the laser scanning area at the protrusion point to prevent heat accumulation, and closely monitoring and analyzing the quality of the protrusion point after molding.

[0019] In this method, the scraper braking system includes a scraper strip drive mechanism and a clamping device on the side of the scraper, which can achieve multiple constraints on the scraper in a limited space; the non-working point of the scraper is relative to the working position of the scraper. Any part outside the normal working length segment that is not in contact with the printer forming platform is the storage location of the abnormal protrusion detection and capture point on the scraper strip.

[0020] In the device implementing this printing solution, the doctor blade of the rotating belt structure is driven by two drive wheels, and a pressure detection device is installed at the bottom between the two rotating shafts, so that the doctor blade is directly facing the pressure detection contact point, improving the sensitivity of receiving abnormal protrusions. Simultaneously, a metal cover plate, installed on a fixed post between the two rotating shafts, effectively restrains the doctor blade. This restraint is essentially a unidirectional limitation on the horizontal direction of the doctor blade, not only acting as a brake and positioning mechanism during normal operation but also enhancing the stability of the doctor blade in the powder scraping direction.

[0021] The pressure detection device in this solution covers the entire working length of the scraper, ensuring that data can be collected for any abnormal protrusions at any working position; the width of the brake cover completely covers the upper and lower areas of the rotating strip scraper, ensuring thorough braking and overall stability.

[0022] Compared with the prior art, the beneficial effects of the present invention are: it can avoid abnormal protrusions in time, which not only protects the scraper but also avoids the waste caused by the workpiece being printed halfway; it can provide real-time feedback on abnormal point information and automatically modify parameters to stop the growth of protrusions or even gradually eliminate them, fundamentally solving all the problems caused by abnormal protrusions; and it prevents printing failures caused by scraper damage or unattended printing equipment during the printing process. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of an application state structure of the present invention.

[0024] Figure 2 This is a schematic diagram of a scraper mechanism according to the present invention.

[0025] Figure 3 yes Figure 2 A partially enlarged structural diagram of the medium pressure detection device.

[0026] Figure 4 This is a schematic diagram of a brake cover structure according to the present invention.

[0027] Figure 5 This is a schematic diagram of the extrusion process when encountering abnormal protrusions according to the present invention.

[0028] In the diagram: 1. Molding box, 2. Scraper mechanism, 201. Scraper holder, 202. First rotating shaft, 203. Second rotating shaft, 204. First drive wheel, 205. Second drive wheel, 206. Scraper, 207. Brake cover plate, 208. Pressure detection device, 209. Fixed column, 210. Electromagnet, 3. Powder storage cylinder, 4. Molding platform, 5. Molding cylinder. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0030] This embodiment discloses an additive manufacturing printing method to prevent squeegee deformation. Based on the powder-spreading laser additive manufacturing process for printing metal parts, the designed 3D model of the part is first layered and sliced ​​according to the printing thickness. Each layer requires a squeegee powder-spreading action. Specifically, while the squeegee 206 moves to spread powder, it remains stable. When the squeegee 206 encounters an abnormal protrusion, it transmits a pressure signal to the pressure detection device 208. After the current layer is powder-spread, the squeegee 206 performs the following actions: the squeegee 206 braking system is released, and the drive mechanism rotates the squeegee 206, displacing the squeegee point that was squeezed and rubbed by the abnormal protrusion to a non-working position. Then, the squeegee 206 remains stable and continues to move and spread powder. Simultaneously, the information acquisition system records the abnormal protrusion position information, and the computer obtains the position of the abnormal protrusion in the current layer based on the squeegee 206's movement time and distance, and the pressure point feedback from the pressure detection device 208.

[0031] In this method, the scraper 206 is a flexible scraper strip, which is a rotating belt composed of a set of wheels.

[0032] The scraper braking system includes a drive mechanism that rotates the scraper 206, and a clamping device on the side of the scraper 206. The non-working point is the non-contact portion of the scraper 206 outside the normal working length of the printer forming platform 4; in this embodiment, it refers to a scraper strip above the rotating belt.

[0033] A scraper device for an additive manufacturing printing method to prevent scraper deformation includes a forming box 1, a forming platform 4 located inside the forming box 1, a forming cylinder 5 disposed in the forming platform 4, a scraper mechanism 2 cooperating with the forming platform 4, and a powder storage cylinder 3 located at the initial position of the forming cylinder 5 and the scraper mechanism 2.

[0034] Scraper mechanism 2 Figure 2 As shown, the tool holder includes a tool holder body 201, with a scraper 206 at its bottom end. The scraper 206 is a flexible scraper strip ring, positioned on two drive wheels, similar to a belt wrapped around a pulley. The two drive wheels are a first drive wheel 204 and a second drive wheel 205, respectively positioned on the rotating shafts at both ends of the bottom of the tool holder body 201, namely the first rotating shaft 202 and the second rotating shaft 203. The two drive wheels have identical structures, with scraper strip grooves on their surfaces.

[0035] Two fixing posts 209 are provided between the first rotating shaft 202 and the second rotating shaft 203, such as Figure 3As shown, an electromagnet 210 is provided at the end of the fixing post 209. A brake cover plate 207 is provided on the outside of the scraper 206, which cooperates with both the side of the scraper 206 and the fixing post 209. The width of the brake cover plate 207 is greater than or equal to the width of the rotating strip scraper, that is, the brake cover plate 207 completely covers the upper and lower sections of the scraper 206.

[0036] The brake cover 207 is provided with two guide sleeves that mate with the fixed post 209, such as Figure 4 As shown, the bottom of the guide sleeve is a magnetic body that works with the electromagnet, and it can be made directly from an iron plate.

[0037] A pressure detection device 208 is provided on the tool holder body 201. The pressure detection device 208 faces the side of a working length section below the rotating strip scraper. The length covered by the pressure detection device 208 is greater than or equal to the working length of the scraper 2.

[0038] The information collection system includes camera and video camera hardware and software tools.

[0039] Working principle and process:

[0040] Normal operating state: The blade holder 201 moves the scraper 206 left and right to spread powder. The first rotating shaft 202 and the second rotating shaft 203 are locked and fixed to keep the scraper 206 stable and not rotate. At this time, the electromagnet 210 on the fixed column 209 attracts the brake cover plate 207, and the brake cover plate 207 presses the scraper 206 against the pressure detection device 208, so that the scraper 206 remains stable and spreads powder evenly.

[0041] If the raised points are higher than the normal powdering height, such as Figure 5 As shown, the movement of the scraper 206 is obstructed. Since the scraper 206 (scraper strip) is made of rubber and its bottom is flexible and deformable, the scraper strip bends in the opposite direction of the scraper 206 to avoid the protrusion. At this time, pressure is immediately applied to the pressure detection device 208. After the current layer of powder is laid, due to the detection of abnormal pressure during the powder laying process, the scraper 206 performs the following actions under the control system: the electromagnet 210 on the fixing post 209 is de-energized, the brake cover 207 releases the pressure constraint on the scraper 206 (scraper strip), the first rotating shaft 202 and the second rotating shaft 203 rotate, driving the first drive wheel 204 and the second drive wheel 205 to rotate, thereby driving the scraper 206 (scraper strip) to rotate. It stops after rotating a certain distance, causing the scraper point that was squeezed and rubbed by the protrusion to shift to the upper part of the rotating strip of the scraper 206. Then, the electromagnet 210 on the fixing post 209 is energized, and the brake cover 207 re-presses the scraper strip.

[0042] This allows the scraper 206 (scraper strip) to be moved, preventing the protruding points from repeatedly rubbing against the same spot on the scraper 206 (scraper strip) and damaging it. Printing continues as usual, preventing the printed parts from being abandoned halfway. A camera takes a picture of the current printed surface, and the computer analyzes the scraper 206's movement time and distance, along with the pressure point feedback from the pressure detection device 208, to determine the location of the protruding points on the current layer, and then performs subsequent processing.

[0043] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An additive manufacturing printing method for preventing scraper deformation, characterized in that, During the toner application process, the scraper is stabilized by a scraper braking system, which includes a drive mechanism that rotates the scraper and a clamping device on the side of the scraper. When the scraper encounters an abnormal protrusion, it transmits a pressure signal to a pressure detection device. After the current layer of toner application is completed, the scraper performs the following actions: the scraper braking system is released, and the drive mechanism rotates the scraper, causing the scraper point that was squeezed and rubbed by the abnormal protrusion to move to a non-working point. The non-working point is the non-contact part between the scraper and the printer forming platform outside the normal working length. At this time, the scraper is stabilized and continues to move and apply toner. Simultaneously, the information acquisition system records the abnormal protrusion information. The computer obtains the position of the abnormal protrusion in the current layer based on the scraper movement time, distance, and pressure point feedback from the pressure detection device. Based on this position information, the abnormal protrusion is processed, including replenishing toner at the abnormal protrusion, modifying the filling parameters of the next layer slice, and adjusting the power and speed of the laser scanning area of ​​the protrusion point. The scraper is a flexible scraper strip, and the scraper strip is a rotating belt composed of a set of wheels.

2. A scraper device for an additive manufacturing printing method for preventing scraper deformation as described in claim 1, comprising a forming housing (1), a forming platform (4) located within the forming housing, and a scraper mechanism cooperating with the forming platform, characterized in that... The scraper mechanism is provided with a scraper (206) at the bottom end. The scraper is a flexible scraper strip and is positioned on two drive wheels. The two drive wheels are respectively positioned on the rotating shafts provided on the blade holder body (201). A fixing column (209) is provided between the two rotating shafts, and an electromagnet is provided on the fixing column. A brake cover plate (207) is provided on the outside of the scraper, which cooperates with the side of the scraper and the fixing column.

3. The additive manufacturing squeegee device for preventing squeegee deformation according to claim 2, characterized in that, in The tool holder body (201) is equipped with a pressure detection device (208), which is located on the side of a working length section below the rotary strip scraper.

4. The additive manufacturing squeegee device for preventing squeegee deformation according to claim 2, characterized in that, The rotating shaft includes a first rotating shaft (202) and a second rotating shaft (203), and the drive wheel includes a first drive wheel (204) and a second drive wheel (205), with a scraper groove provided on the drive wheel.

5. The additive manufacturing squeegee device for preventing squeegee deformation according to claim 2, characterized in that, The fixing post (209) is provided in several places, and an electromagnet (210) is provided at the end of the fixing post. The brake cover plate (207) is provided with a guide sleeve that cooperates with the fixing post, and the bottom end of the guide sleeve is a magnetic body that cooperates with the electromagnet.

6. The additive manufacturing squeegee device for preventing squeegee deformation according to claim 3, characterized in that, The pressure detection device (208) covers a length greater than or equal to the working length of the scraper (206).

7. The additive manufacturing squeegee device for preventing squeegee deformation according to claim 2, characterized in that, The width of the brake cover (207) is greater than or equal to the width of the rotating strip scraper.

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