Multi-material powder bed additive manufacturing porous negative pressure sand laying and recycling integrated method

Abstract

The present application relates to the technical field of additive manufacturing, and proposes a multi-material powder bed additive manufacturing porous negative pressure sand laying and recycling integrated method, which comprises a forming platform, a rack, a motor, a lifting screw, a guide rail, a sand laying box, a cross beam, a vacuum cylinder, a pipeline, a screening device and a negative pressure adsorption device. The device and method use the negative pressure adsorption device to adsorb and recycle the multi-material sand laid in the forming platform, so that the sand laying surface meets the requirements of flatness and certain thickness, and the recycled mixed sand is separated through the vibration screen of the screening device, and the sand in the screen is classified and put into the sand laying box through the control of the air cylinder, thereby solving the problem of uneven sand laying surface caused by easy wear and sand sticking of the sand scraping plate, and realizing the real-time recycling and classified reuse integration of multi-material sand.

Description

Technical Field

[0001] This invention relates to the sand molding process in the field of additive manufacturing technology, and more particularly to an integrated method for porous negative pressure sand laying and recycling in multi-material powder bed additive manufacturing. Background Technology

[0002] Additive manufacturing technology is a brand-new product manufacturing technology that breaks down parts into smaller components by slicing them, transforming three-dimensional manufacturing problems into two-dimensional manufacturing. This reduces the difficulty of producing complex products, expands the possibilities for product design and manufacturing, and also has high material utilization and short production cycles, making it a promising technology with broad development prospects.

[0003] Sand mold 3D printing technology is an important branch of additive manufacturing technology. Currently, the most widely used industrial application is sand mold printing technology based on the microdroplet jetting principle. This involves spraying a binder onto the surface of molding sand to bond and solidify the sand, accumulating layers to obtain the final complex shape mold. Sand mold 3D printing technology has overturned the shortcomings of traditional casting industry, such as slow manual molding speed and long model manufacturing cycle. It has achieved automated molding, shortened the manufacturing cycle, and reduced production costs, and is increasingly being used in the manufacturing of small batches of complex castings with high added value.

[0004] During sand molding, the constant friction between the scraper and the molding sand can easily lead to wear and sand adhesion issues over long-term use, resulting in an uneven sand surface. In multi-material molding sand printing, excess molding sand is mixed with the scraper and transferred to the recycling device, making it impossible to achieve recycling, sorting, and reuse. Summary of the Invention

[0005] To address the aforementioned issues, this invention discloses an integrated device and method for multi-material powder bed additive manufacturing with porous negative pressure sand laying and recycling. This device primarily solves the problem of integrating multi-material powder bed sand laying and molding sand recycling during sand mold 3D printing.

[0006] This invention discloses an integrated device for porous negative pressure sand spreading and recovery in multi-material powder bed additive manufacturing, comprising a forming platform, a frame, a motor, a lifting screw, guide rails, a sand spreading box, a crossbeam, a vacuum cylinder, pipes, a screening device, and a negative pressure adsorption device. The motor and lifting screw are mounted at the bottom of the frame and connected by a synchronous belt. The sand spreading box is connected to the frame via guide rails on both sides. The top of the sand spreading box is fixedly connected to the crossbeam, and the screening device is mounted on the crossbeam. The screening device can move horizontally to dispose of sand of different materials. The sand spreading box is horizontally fixedly connected to the negative pressure adsorption device, which is also sealed to the vacuum cylinder via pipes.

[0007] As a further design of the present invention, after the sand is laid, there is no need to scrape off the excess molding sand with a sand scraper. Instead, the excess molding sand is introduced into the negative pressure adsorption device to adsorb the molding sand laid on the forming platform.

[0008] As a further design of the present invention, the negative pressure adsorption device has uniformly distributed pressure regulating valves, which are used to adjust the adsorption pressure at different positions to achieve uniform adsorption of different material powders.

[0009] As a further design of the present invention,

[0010] The screening device consists of several layers of screens with different mesh sizes from top to bottom, and a vibrator. Each screen is equipped with a limiting frame above it. The front end of the screen is connected to a movable plate. The two ends of the movable plate are connected to the cylinder shaft of a movable cylinder. The movable cylinder is fixed on the limiting frame. The screen vibrates to screen molding sand of different particle sizes. The cylinder controls the movement of the bottom plane of the screen to put the screened molding sand back into the sand-laying box, thereby realizing the classification, recycling and reuse of molding sand of different materials.

[0011] The screening device consists of multiple layers of screens with different mesh sizes and cylinders. It screens molding sand of different particle sizes by vibrating the screens and controls the movement of the bottom plane of the screen by the cylinders to put the screened molding sand back into the sand-laying box, thereby realizing the classification, recycling and reuse of molding sand of different materials.

[0012] As a further design of the present invention, an electromagnetic valve control switch is installed below the vacuum cylinder, and the stored recycled molding sand is dropped into the screening device by controlling the electromagnetic valve control switch.

[0013] A multi-material powder bed additive manufacturing method integrating porous negative pressure sand laying and recycling, the method comprising the following steps:

[0014] S1: Select several suitable molding sands according to the casting characteristics, and put the molding sands of different materials into different material cylinders of the sand-laying box respectively;

[0015] S2: Turn on the switch for sand spreading operation. The sand spreading box and the negative pressure adsorption device start simultaneously. The sand spreading box spreads molding sand of different materials onto the forming platform. Adjust the pressure of the pressure regulating valve on the negative pressure adsorption device according to the specific gravity of different molding sands to adsorb and store excess molding sand in the vacuum cylinder.

[0016] S3: Spray adhesive onto the laid molding sand surface to perform the printing operation. After printing is completed, the forming platform moves down by one layer thickness. Repeat the sand laying and printing operations until the workpiece is printed.

[0017] S4: Open the solenoid valve control switch below the vacuum cylinder to put the adsorbed multi-material mixed powder into the sieving device;

[0018] S5: Turn on the vibration mode of the screening device to screen the mixed molding sand until the molding sand of different materials is completely separated, then turn off the vibration mode;

[0019] S6: The screening device controls the cylinders to open the screen from bottom to top, put the molding sand into the sand laying box, and moves the screening device horizontally to align the screen with the different types of sand laying openings.

[0020] S7: Remove the printed sand mold workpiece and clean the worktable.

[0021] The molding sand material includes powder materials such as silica sand, chromite sand, ceramic powder, and zircon sand.

[0022] The molding sand made of different materials uses different particle sizes, so that the classification and recycling of molding sand can be achieved by screening through sieves of different mesh sizes.

[0023] The screening device can screen out excess molding sand during sand laying, and can also screen out the molding sand remaining on the forming platform after the printed parts are removed.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. Compared with commonly used sand molding printing equipment, it creatively replaces the scraper with a flexible adsorption device, which can achieve a smooth sand-laying surface and recover excess molding sand in real time.

[0026] 2. The pressure of the suction nozzles at different locations on the negative pressure adsorption device is adjustable, allowing for real-time adjustment of the negative pressure for molding sand of different materials in different areas.

[0027] 3. The recycled multi-material molding sand is reused through automated screening, separation and precise classification, saving raw materials. Attached Figure Description

[0028] Figure 1 An integrated device for additive manufacturing of porous negative pressure sand laying and recycling in multi-material powder bed;

[0029] Figure 2 This is a schematic diagram of the adsorption device structure;

[0030] Figure 3 This is a schematic diagram showing the connection between the adsorption device and the vacuum cylinder;

[0031] Figure 4 This is a schematic diagram of the screening device.

[0032] Figure 5 for Figure 1 Another view; Implementation

[0033] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0034] like Figure 1-5 As shown, this invention provides an integrated device for porous negative pressure sand spreading and recycling in multi-material powder bed additive manufacturing, comprising a forming platform 1, a frame 2, a motor 3, a lifting screw 4, a guide rail 5, a sand spreading box 6, a crossbeam 7, a vacuum cylinder 8, a pipe 9, a screening device 10, and a negative pressure adsorption device 11. The motor 3 and the lifting screw 4 are installed at the bottom of the frame, and are connected by a synchronous belt to achieve the lifting and lowering of the forming platform 1.

[0035] The sand-laying box 6 is connected to the frame 2 via guide rails 5 on both sides, enabling the sand-laying device to move left and right and lay multiple materials of molding sand. The sand-laying box 6 is horizontally fixedly connected to the negative pressure adsorption device 11, and the negative pressure adsorption device 11 is sealed to the vacuum material cylinder 8 via pipe 9, which is used to recover the excess molding sand laid by the sand-laying box 6 and store it in the vacuum material cylinder 8.

[0036] The sand-laying box 6 is fixedly connected to the crossbeam 7, and the screening device 10 is installed on the crossbeam 7. The screening device can move horizontally along the crossbeam 7 to classify and drop molding sand of different materials into the sand-laying box 6. After the sand is laid, there is no need to scrape off the excess molding sand with a sand scraper. The excess molding sand on the forming platform 1 is introduced into the negative pressure adsorption device 11. The negative pressure adsorption device 11 has uniformly distributed pressure regulating valves to adjust the adsorption pressure at different parts to achieve uniform adsorption of powders of different materials.

[0037] The screening device 10 consists of multiple layers of screens with different mesh sizes and cylinders, and screens different particle sizes of molding sand by vibrating the screens.

[0038] The screening device 10 consists of several layers of screens 10-1 with different mesh sizes from top to bottom, and a vibrator. Each screen 10-1 has a limiting frame 10-4 above it. A movable plate 10-2 is connected to the front end of each screen 10-1. Both ends of the movable plate 10-2 are connected to the cylinder shaft of a movable cylinder 10-3. The movable cylinder 10-3 is fixed to the limiting frame 10-4. Different particle sizes of molding sand are screened by the screen vibration. The movement of the bottom plane of the screen is controlled by the cylinder, allowing the screened molding sand to be placed back into the sand-laying box 6, thus achieving the classification, recycling, and reuse of molding sand of different materials. A solenoid valve control switch is installed below the vacuum cylinder 8, allowing the stored recycled molding sand to fall into the screening device 10.

[0039] A multi-material powder bed additive manufacturing method integrating porous negative pressure sand laying and recycling, the method comprising the following steps:

[0040] S1: Select different molding sands such as silica sand, chromite sand, and zircon sand as composite mold structure materials according to the casting characteristics, and put the molding sands of different materials into different material cylinders of the sand laying box 6 respectively;

[0041] S2: Turn on the sand spreading operation switch. The sand spreading box 6 and the negative pressure adsorption device 11 start at the same time. The sand spreading box 6 spreads molding sand of different materials onto the forming platform 1. The pressure of the pressure regulating valve on the negative pressure adsorption device is adjusted to between 50L / S and 150L / S according to the specific gravity of the molding sand. The negative pressure applied to the sand spreading part with a higher specific gravity is greater. The excess molding sand is adsorbed and stored in the vacuum cylinder 8.

[0042] S3: Spray adhesive onto the prepared molding sand surface for printing. After printing, the forming platform is lowered by 0.3-0.6mm. Repeat the sand laying and printing process until the workpiece is printed.

[0043] S4: Open the solenoid valve control switch below the vacuum cylinder 8 to put the adsorbed multi-material mixed powder into the sieving device;

[0044] S5: Turn on the vibration mode of the screening device 10 to screen the mixed molding sand until the molding sand of different materials is completely separated, then turn off the vibration mode.

[0045] S6: The screening device 10 controls the cylinders to open the screen from bottom to top, puts the molding sand into the sand laying box 6, and moves the screening device horizontally to align the screen opening with the different types of sand laying openings, thus completing the recycling of molding sand.

[0046] S7: Remove the printed sand mold workpiece and clean the worktable.

[0047] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features.

Claims

1. A multi-material powder bed additive manufacturing method integrating porous negative pressure sand laying and recycling, characterized in that, This invention relates to an integrated device for porous negative pressure sand spreading and recycling based on additive manufacturing of powder bed materials. The device includes a forming platform (1), a frame (2), a motor (3), a lifting screw (4), a guide rail (5), and a sand spreading box (6). Its features include a crossbeam (7), a vacuum cylinder (8), a pipe (9), a screening device (10), and a negative pressure adsorption device (11). The frame (2) is equipped with a motor (3) and a lifting screw (4) at its bottom, connected by a synchronous belt. The sand spreading box (6) is connected to the frame (2) via guide rails (5) on both sides. The top of the sand spreading box (6) is fixedly connected to the crossbeam (7), and the screening device (10) is installed on the crossbeam (7). The screening device (10) moves horizontally to collect sand from different materials. The sand spreading box (6) and the vacuum cylinder (8), pipe (9), screening device (10), and negative pressure adsorption device (11) are also included. The negative pressure adsorption device (11) is horizontally fixed and connected, and the negative pressure adsorption device (11) is sealed to the vacuum cylinder (8) through the pipe (9); the screening device (10) consists of several layers of screens (10-1) with different mesh sizes from top to bottom and a vibrator; each screen (10-1) is provided with a limiting frame (10-4) above it; the front end of the screen (10-1) is connected to a movable plate (10-2); the two ends of the movable plate (10-2) are respectively connected to the cylinder shaft of the movable cylinder (10-3); the movable cylinder (10-3) is fixed on the limiting frame (10-4); the different particle sizes of molding sand are screened by the screen vibration, and the movement of the bottom plane of the screen is controlled by the cylinder to put the screened molding sand back into the sand laying box (6), thereby realizing the classification, recycling and reuse of molding sand of different materials; the method includes the following steps: S1: Select several suitable molding sands according to the casting characteristics, and put the molding sands of different materials into different material cylinders of the sand laying box (6); S2: Turn on the sand spreading operation switch. The sand spreading box (6) and the negative pressure adsorption device (11) start at the same time. The sand spreading box (6) spreads molding sand of different materials onto the forming platform (1). The pressure of the pressure regulating valve on the negative pressure adsorption device (11) is adjusted according to the specific gravity of different molding sands. The excess molding sand is adsorbed and stored in the vacuum cylinder (8). S3: Spray adhesive on the laid molding sand surface to perform printing operation. After printing is completed, the forming platform (1) moves down by one layer thickness. Repeat the sand laying and printing operation until the workpiece is printed. S4: Open the solenoid valve control switch below the vacuum cylinder (8) and put the adsorbed multi-material mixed powder into the sieving device (10); S5: Turn on the vibration mode of the screening device (10) to screen the mixed molding sand until the molding sand of different materials is completely separated, and then turn off the vibration mode. S6: The screening device (10) controls the cylinder to open the screen from bottom to top, puts the molding sand into the sand laying box (6), and moves the screening device (10) horizontally to align the screen with the different types of sand laying openings. S7: Remove the printed sand mold workpiece and clean the worktable.

2. The integrated method for porous negative pressure sand laying and recycling in multi-material powder bed additive manufacturing according to claim 1, characterized in that: The negative pressure adsorption device (11) is equipped with several pressure regulating valves that are evenly distributed.

3. The integrated method for porous negative pressure sand laying and recycling in multi-material powder bed additive manufacturing according to claim 1, characterized in that: A solenoid valve control switch is installed below the vacuum cylinder (8). The stored recycled molding sand is dropped into the screening device (10) by controlling the solenoid valve switch.

4. The integrated method for porous negative pressure sand laying and recycling in multi-material powder bed additive manufacturing according to claim 1, characterized in that, The molding sand material includes silica sand, chromite sand, ceramic powder, and zircon sand powder.

5. The integrated method for porous negative pressure sand laying and recycling in multi-material powder bed additive manufacturing according to claim 1, characterized in that, The molding sand made of different materials uses different particle sizes, so that the classification and recycling of molding sand can be achieved by screening through sieves of different mesh sizes.

6. The integrated method for porous negative pressure sand laying and recycling in multi-material powder bed additive manufacturing according to claim 1, characterized in that, The screening device (10) can screen out excess molding sand during sand laying, and can also screen out the remaining molding sand on the forming platform (1) after the printed parts are taken out.

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