Powder spreading device, forming equipment and forming method for selective laser sintering

Abstract

The present invention provides a powder spreading device for selective laser sintering, wherein a drum is arranged in a mounting seat, and the two ends are movably connected to a guide connecting plate and a connecting seat respectively, and the connecting seat is connected to a guide rail slider mechanism, and an external motor drives the powder spreading device to move and spread powder on the guide rail slider mechanism; there are two guide mechanisms, which are arranged in parallel on the left and right sides of the drum at a set angle, and the front and rear sides of the guide mechanism are fixedly connected by a guide connecting plate and a guide conversion mechanism, and a plurality of guide scrapers and scraper gears are evenly arranged on the upper and lower sides of the guide mechanism, and the guide scrapers are connected to an angle conversion mechanism arranged on the guide mechanism through the scraper gear to change the guide angle; the guide conversion mechanism realizes the up and down movement of the guide mechanism along a set track by connecting a conversion motor. In the powder spreading process, the powder material is arranged along the direction of the guide scraper of the guide mechanism, thereby avoiding the single-direction distribution of the composite substrate in the powder material and improving the anisotropic mechanical properties of the workpiece.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to a powder spreading device, forming equipment and a forming method thereof for selective laser sintering. Background Art

[0002] Selective laser sintering is a method of manufacturing three-dimensional objects by selectively fusing multiple powder layers. This method allows the three-dimensional entity to be obtained by laser sintering multiple overlapping layers of powder according to the three-dimensional image of the object to be produced without the use of tool processing. This method is mainly completed using thermoplastic polymers. Patents US6136948 and WO9606881 describe in detail this method of manufacturing three-dimensional objects using powdered polymers.

[0003] At present, there are many methods for material modification, and a wide variety of polymer composite powder materials with orientation differences have been produced. Taking fiber modified materials as an example, this material can greatly improve the mechanical properties of the material. Patent CN103951971A makes a detailed description of carbon fiber modified PA12. However, since the fibers will be oriented during the selective laser sintering and powder laying process, resulting in differences in performance on the horizontal plane, the mechanical properties along the direction of the fiber long axis are much higher than the performance perpendicular to the direction of the fiber long axis, resulting in uneven overall performance of the product. Summary of the invention

[0004] In view of the above-mentioned technical problems existing in the prior art, the present invention provides a powder spreading device for selective laser sintering, which is used to change the orientation of polymer composite powder materials. The powder spreading device includes a roller and a mounting seat thereof, two guide mechanisms with a certain angle, a guide conversion mechanism and an angle conversion mechanism. During the powder spreading process, the powder material is arranged along the direction of the guide scraper of the guide mechanism, so that the powder materials between adjacent layers are at a certain angle, thereby avoiding the single-direction distribution of the composite matrix in the powder material, and making the composite matrix distributed in a spiral shape in the Z direction in the workpiece, thereby improving the problem of uneven mechanical properties of the material in the XY plane, and at the same time improving its mechanical properties in the Z direction.

[0005] The present invention provides a powder spreading device for selective laser sintering, which is used for changing the orientation of polymer composite powder materials, and comprises a mounting seat, a connecting seat, a guide rail slider mechanism, a roller, a guiding mechanism, an angle conversion mechanism, a guide connecting plate and a guiding conversion mechanism; the roller is arranged in the mounting seat, one end of the roller is movably connected to the guide connecting plate, and the other end is movably connected to the connecting seat through the guiding conversion mechanism, the connecting seat is connected to the guide rail slider mechanism, and the powder spreading device is driven by an external motor to move and spread powder on the guide rail slider mechanism; the number of the guiding mechanisms is two, and they are arranged in parallel on the left and right sides of the roller at a set angle, the front and rear sides of the guiding mechanism are fixedly connected by the guiding connecting plate and the guiding conversion mechanism, and a plurality of guiding scrapers and scraper gears are evenly arranged on the upper and lower sides of the guiding mechanism, the guiding scrapers are connected to the angle conversion mechanism arranged on the guiding mechanism through the scraper gears to change the guiding angle; the guiding conversion mechanism realizes the up and down movement of the guiding mechanism along the set track by connecting the conversion motor.

[0006] As a further preferred embodiment of the present invention, the angle conversion mechanism includes a guide mounting plate, a guide rack, a guide scraper bar connecting rod, a guide bearing, a guide motor fixing seat, connecting screws and a guide motor. The guide scraper bar is connected to the guide scraper bar connecting rod by a connecting screw. One end of the guide scraper bar connecting rod is connected to the guide mounting plate by a guide bearing, and the other end is provided with a scraper bar gear. The scraper bar gear and the guide scraper bar connecting rod are fixedly matched, and the scraper bar gear and the guide rack are transmission matched.

[0007] As a further preferred embodiment of the present invention, the thickness of the guide scraper strip is 1-10 mm, and the length of the guide scraper strip is 1-10 mm.

[0008] As a further preferred embodiment of the present invention, the distance between adjacent guide scrapers is 1-10 mm.

[0009] As a further preferred embodiment of the present invention, the angle conversion mechanism further comprises a guide motor and a guide motor fixing seat, and the guide motor is also provided with a motor gear for transmission cooperation with the guide rack.

[0010] As a further preferred embodiment of the present invention, the guide mechanism is arranged around the drum at a set angle, wherein 0°<set angle≤180°, and the guide mechanism is arranged upward along the opening of the drum.

[0011] The guide conversion includes a conversion motor, a conversion belt, a conversion connecting plate, a conversion fixed gear, a conversion center axis, a conversion bearing, a conversion movable gear and a conversion motor gear. The upper and lower ends of the conversion belt are respectively engaged with the conversion motor gear and the conversion movable gear, and the left and right ends of the conversion belt are respectively engaged with two conversion fixed gears. The conversion fixed gear is fixedly connected to the conversion connecting plate, and the conversion movable gear is rotationally connected to the conversion connecting plate around the conversion center axis through the conversion bearing.

[0012] As a further preferred embodiment of the present invention, an initial angle formed between the initial direction of the guide scraper strip and the drum is an acute angle or a right angle.

[0013] As a further preferred embodiment of the present invention, with the forward direction of the powder spreading device as the front, when spreading the powder, the horizontal position of the guide scraper in the front guide mechanism is equal to the horizontal position of the lowest point of the roller, and the horizontal position of the guide scraper in the rear guide mechanism is 0.5-5mm higher than the lowest point of the roller.

[0014] The present invention also provides a forming device for selective laser sintering, comprising the powder spreading device for selective laser sintering.

[0015] The present invention also provides a forming method for selective laser sintering, which is implemented using the forming device and includes the following steps:

[0016] Step 1: Spread a layer of polymer composite powder with different orientations. The horizontal position of the guide scraper on one side of the roller is equal to the horizontal position of the lowest point of the roller through the guide conversion mechanism. The guide scraper on one side of the roller arranges the powder material along its moving direction. The roller fills the powder surface dents caused by the guide scraper in front. After the powder is spread, laser sintering is performed.

[0017] Step 2: After sintering is completed, powder is spread again. At this time, the powder spreading device moves back, and the horizontal position of the guide scraper on the other side of the drum is equal to the horizontal position of the lowest point of the drum through the guide conversion mechanism. The guide scraper is used to arrange the powder spreading material along its moving direction, and the drum fills the powder surface dents caused by the guide scraper. After powder spreading, laser sintering is performed;

[0018] Step 3: before the powder spreading action in step 1 and / or step 2 begins, the guide motor is turned on to drive the motor gear to rotate. At the same time, there is a transmission relationship between the scraper gear and the guide rack, thereby driving the guide scraper connecting rod and the guide scraper to rotate, changing the angle of the guide scraper. When the angle is rotated to the required angle, the guide motor stops working;

[0019] Step 4: Repeat steps 1 to 3 until all sintering layers are sintered to obtain a sample.

[0020] The present invention provides a powder spreading device, forming equipment and forming method for selective laser sintering. Guide mechanisms are introduced on both sides of a roller. During the powder spreading process, the guide scrapers of the guide mechanisms arrange the composite substrate in the powder material along the direction of the guide scrapers. At the same time, each time the powder is spread, the guide scrapers of the two guide mechanisms rotate in the same direction at different angles. The arrangement direction of the composite substrate between each layer of powder is different. Then, the roller is used to make the powder surface smooth, which not only realizes the change of the arrangement direction of the composite substrate, but also does not cause defects in the sintered parts due to the uneven powder surface during sintering. Finally, the composite substrate in the sintered parts will be distributed in a spiral arrangement in the Z direction, which not only improves the anisotropy of the mechanical properties of the polymer composite powder material in the XY plane, but also can improve its Z-direction performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of a powder spreading device for selective laser sintering in the present invention;

[0022] Figure 2 for Figure 1 Bottom view of

[0023] Figure 3 It is a structural schematic diagram of the angle conversion mechanism in the present invention;

[0024] Figure 4 is another structural schematic diagram of the angle conversion mechanism in the present invention;

[0025] Figure 5 It is a structural schematic diagram of the guide conversion mechanism in the present invention;

[0026] Figure 6 for Figure 5 Front view of .

[0027] : Illustration symbols: 1. mounting seat; 2. connecting seat; 3. guide rail slider mechanism; 4. roller; 5. guide mechanism; 51. guide scraper; 6. angle conversion mechanism; 61. guide mounting plate; 62. motor gear; 63. guide rack; 64. guide scraper connecting rod; 65. guide bearing; 66. scraper gear; 67. connecting screw; 68. guide motor; 69. guide motor fixing seat; 7. guide connecting plate; 8. guide conversion mechanism; 81. conversion motor; 82. conversion belt; 83. conversion connecting plate; 84. conversion fixed gear; 85. conversion center shaft; 86. conversion bearing; 87. conversion movable gear; 88. conversion motor gear. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present invention, the present invention is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this specification are for illustrative purposes only.

[0029] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification and in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0030] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the polymer composite powder material is described by taking a polymer powder material with fiber as a composite matrix as an example, which will be further described in detail below in conjunction with the drawings and embodiments of the specification.

[0031] like Figure 1-6 As shown, the present invention provides a powder spreading device for selective laser sintering, which is used to change the orientation of polymer composite powder materials, including a mounting seat 1, a connecting seat 2, a guide slider mechanism 3, a roller 4, a guide mechanism 5, an angle conversion mechanism 6, a guide connecting plate 7 and a guide conversion mechanism 8; the roller 4 is arranged in the mounting seat 1, one end of the roller 4 is movably connected to the guide connecting plate 7, and the other end is movably connected to the connecting seat 2 through the guide conversion mechanism 8, the connecting seat 2 is connected to the guide slider mechanism 3, and the powder spreading device is driven by an external motor to move and spread powder on the guide slider mechanism 3; the number of the guide mechanisms 5 is two, and they are arranged in parallel on the left and right sides of the roller 4 at a set angle, the front and rear sides of the guide mechanisms 5 are fixedly connected by the guide connecting plate 7 and the guide conversion mechanism 8, and a plurality of guide scrapers 51 and scraper gears 66 are evenly arranged on the upper and lower sides of the guide mechanism 5, and the guide scrapers 51 are connected to the angle conversion mechanism 6 arranged on the guide mechanism 5 through the scraper gear 66 to change the guide angle; the guide conversion mechanism 8 realizes the up and down movement of the guide mechanism 5 along the set track by connecting the conversion motor 81.

[0032] In the present invention, the angle conversion mechanism 6 includes a guide mounting plate 61, a guide rack 63, a guide scraper connecting rod 64, a guide bearing 65, a guide motor fixing seat 69, a connecting screw 67 and a guide motor 68. The guide scraper 51 is connected to the guide scraper connecting rod 64 by the connecting screw 67. One end of the guide scraper connecting rod 64 is connected to the guide mounting plate 61 by the guide bearing 65, and the other end is equipped with a scraper gear 66. The scraper gear 66 is fixedly matched with the guide scraper connecting rod 64, and the scraper gear 66 is transmission matched with the guide rack 63.

[0033] Further preferably, the thickness of the guide scraper 51 is 1-10 mm, the length of the guide scraper 51 is 1-10 mm, and the distance between adjacent guide scrapers 51 is 1-10 mm. Obviously, the spacing between adjacent guide scrapers 51 will also affect the fiber guidance, which will not be elaborated here.

[0034] In the present invention, specifically, the angle conversion mechanism 6 further includes a guide motor 68 and a guide motor fixing seat 69 . The guide motor 68 is also provided with a motor gear 62 , which performs transmission cooperation with the guide rack 63 .

[0035] In the present invention, the guide mechanism 5 is at a set angle around the drum 4, wherein 0°<set angle≤180°, and the guide mechanism 5 is arranged upward along the opening of the drum 4. In this embodiment, the guide mechanism 5 is at a set angle of 120° around the drum.

[0036] Specifically, the guide conversion mechanism 8 includes a conversion motor 81, a conversion belt 82, a conversion connecting plate 83, a conversion fixed gear 84, a conversion center axis 85, a conversion bearing 86, a conversion movable gear 87 and a conversion motor gear 88. The upper and lower ends of the conversion belt 82 are respectively engaged with the conversion motor gear 88 and the conversion movable gear 87, and the left and right ends of the conversion belt 82 are respectively engaged with two conversion fixed gears 84. The conversion fixed gear 84 is fixedly connected to the conversion connecting plate 83, and the conversion movable gear 87 is rotationally connected to the conversion connecting plate 83 through the conversion bearing 86 around the conversion center axis 85.

[0037] Further preferably, the initial angle formed by the initial direction of the guide scraper strip 51 and the drum 4 is an acute angle or a right angle. In this embodiment, the initial angle formed by the initial direction of the guide scraper strip 51 and the drum 4 is 45°.

[0038] In the present invention, the direction in which the powder spreading device moves forward is the front, and when spreading the powder, the horizontal position of the guide scraper 51 in the front guide mechanism 5 is equal to the horizontal position of the lowest point of the roller 4, and the horizontal position of the guide scraper 51 in the rear guide mechanism 5 is 0.5-5mm higher than the lowest point of the roller 4. In this embodiment, when spreading the powder, the horizontal position of the guide scraper 51 in the front guide mechanism 5 is equal to the horizontal position of the lowest point of the roller 4, and the horizontal position of the guide scraper 51 in the rear guide mechanism 5 is 3mm higher than the lowest point of the roller 4.

[0039] The present invention also provides a forming device for selective laser sintering, including a powder spreading device for selective laser sintering. It is worth noting that the forming device for selective laser sintering specifically includes a powder feeding cylinder, a forming cylinder, a laser, a galvanometer scanning system, etc., which are all prior arts and will not be described in detail here.

[0040] The present invention also provides a forming method for selective laser sintering, which is implemented using the above-mentioned forming device and includes the following steps:

[0041] Step 1, the powder feeding cylinder rises to a certain height and the working cylinder drops to a certain height at the same time, with the direction of the powder spreading device as the front. When spreading the fiber composite polymer powder material, the guide conversion mechanism 8 is used to make the horizontal position of the guide scraper 51 in the guide mechanism 5 in front of the powder spreading equal to the horizontal position of the lowest point of the roller 4, while the horizontal position of the guide scraper 51 in the rear guide mechanism 5 is 3 mm higher than the roller 4. When spreading the powder, the front guide mechanism 5 arranges the fibers in the powder spreading material along the moving direction of the guide scraper 51 through the guide scraper 51 below it, and the roller 4 fills the powder surface dents caused by the front guide mechanism 5, and then laser sintering is performed.

[0042] Step 2, after sintering is completed, powder is spread again. At this time, the powder spreading device moves back, and the guide mechanism 5 that was originally in the front of the powder spreading becomes the rear of the powder spreading, and the guide mechanism 5 that was originally in the rear of the powder spreading becomes the front of the powder spreading. At this time, before the powder spreading action is needed, the conversion motor 81 of the guide conversion mechanism 8 drives the conversion belt 82 to transmit through the conversion motor gear 88, and drives the conversion connecting plate 83 to rotate around the conversion center axis 85 through the conversion fixed gear 84, so that the horizontal position of the guide scraper 51 in the guide mechanism 5 in front of the powder spreading is equal to the horizontal position of the lowest point of the roller 4, and the horizontal position of the guide scraper 51 in the rear guide mechanism 5 is higher than the roller 4 by a certain height. Then, when the powder spreading action is performed, the front guide mechanism 5 uses the guide scraper 51 below it to arrange the fibers in the powder spreading material into another angle along the moving direction of the guide scraper 51, and the roller 4 fills the powder surface dents caused by the front guide mechanism 5, and then laser sintering is performed.

[0043] Step 3: After two layers of powder are laid, the angle of the guide scraper 51 is changed, and the motor gear 62 is driven to rotate by the guide motor 68, and the motor gear drives the guide rack to move. At the same time, there is a transmission relationship between the scraper gear 66 and the guide rack 63, thereby driving the guide scraper connecting rod 64 and the guide scraper 51 to rotate. When the angle is rotated to the required angle, the guide motor 68 stops working. It should be noted that this embodiment is described by taking the completion of two layers of powder laying as an example. In actual operation, the angle of the guide scraper 51 can be changed for each layer, which will not be repeated.

[0044] Step 4: Repeat steps 1 to 3 until all sintering layers are sintered to obtain a sample.

[0045] The present invention provides a powder spreading device, forming equipment and forming method for selective laser sintering. A guide mechanism is introduced on both sides of a roller 4. During the powder spreading process, the guide scraper 51 of the guide mechanism arranges the composite substrate in the powder material along the direction of the guide scraper 51. At the same time, each time the powder is spread, the guide scrapers 51 of the two guide mechanisms rotate in the same direction at different angles, and the arrangement direction of the composite substrate between each layer of powder is different. Then, the roller 4 is used to make the powder surface smooth, which not only realizes the change of the arrangement direction of the composite substrate, but also does not cause defects in the sintered parts due to the uneven powder surface during sintering. Finally, the composite substrate in the sintered parts will be distributed in a spiral arrangement in the Z direction, which not only improves the anisotropy of the mechanical properties of the polymer composite powder material in the XY plane, but also can improve its Z-direction performance.

[0046] The parameters in Table 1 were used to design the structure of the powder spreading device. Then, the FS3400CF powder material produced by Hunan Huashu High-Tech was used to carry out powder spreading and sintering using the new powder spreading device and the conventional powder spreading device, and the mechanical properties of the sintered parts were tested.

[0047] Table 1 Guide mechanism parameters and mechanical properties of the materials sintered using them

[0048]

[0049] From the results in Table 1, it can be seen that the mechanical properties of the parts obtained by sintering after powder spreading using the powder spreading device of the present invention are higher in the Y and Z directions than those of the conventional roller powder spreading device, which shows that the scheme of the present invention can improve the problem of orientation of mechanical properties of sintering fiber composite powder materials and improve the mechanical properties in the Z direction; the thickness and length of the guide scrapers and the angle difference between the guide scrapers will affect the arrangement of the fibers during powder spreading, and ultimately affect the performance of the parts.

Claims

1. A powder spreading device for selective laser sintering, used to change the orientation of polymer composite powder materials, characterized in that: It includes a mounting seat, a connecting seat, a guide rail slider mechanism, a roller, a guide mechanism, an angle conversion mechanism, a guide connecting plate and a guide conversion mechanism; The roller is arranged in the mounting seat, one end of the roller is movably connected to the guide connecting plate, and the other end is movably connected to the connecting seat through the guide conversion mechanism, the connecting seat is connected to the guide rail slider mechanism, and the powder spreading device is driven by an external motor to move on the guide rail slider mechanism to spread powder; There are two guide mechanisms, which are placed in parallel at a set angle on the left and right sides of the drum. The front and rear sides of the guide mechanism are fixedly connected by a guide connecting plate and a guide conversion mechanism. A plurality of guide scrapers and scraper gears are evenly arranged on the upper and lower sides of the guide mechanism. The guide scrapers are connected to an angle conversion mechanism arranged on the guide mechanism through the scraper gear to change the guide angle. The guide conversion mechanism realizes the up and down movement of the guide mechanism along the set track by connecting the conversion motor; The angle conversion mechanism includes a guide mounting plate, a guide rack, a guide scraper connecting rod, a guide bearing, a guide motor fixing seat, a connecting screw and a guide motor. The guide scraper is connected to the guide scraper connecting rod through a connecting screw. One end of the guide scraper connecting rod is connected to the guide mounting plate through a guide bearing, and the other end is equipped with a scraper gear. The scraper gear is fixedly matched with the guide scraper connecting rod, and the scraper gear is transmission matched with the guide rack. The thickness of the guide scraper strip is 1-10 mm, and the length of the guide scraper strip is 1-10 mm; The angle conversion mechanism also includes a guide motor and a guide motor fixing seat. The guide motor is also equipped with a motor gear for transmission cooperation with the guide rack.

2. The powder spreading device for selective laser sintering according to claim 1, characterized in that: The guide mechanism is arranged around the drum at a set angle, wherein 0°<set angle≤180°, and the guide mechanism is arranged upward along the opening of the drum.

3. The powder spreading device for selective laser sintering according to claim 2, characterized in that: The guide conversion mechanism includes a conversion motor, a conversion belt, a conversion connecting plate, a conversion fixed gear, a conversion center axis, a conversion bearing, a conversion movable gear and a conversion motor gear. The upper and lower ends of the conversion belt are respectively engaged with the conversion motor gear and the conversion movable gear, and the left and right ends of the conversion belt are respectively engaged with two conversion fixed gears. The conversion fixed gear is fixedly connected to the conversion connecting plate, and the conversion movable gear is rotationally connected to the conversion connecting plate around the conversion center axis through the conversion bearing.

4. The powder spreading device for selective laser sintering according to claim 3, characterized in that: The initial angle formed by the initial direction of the guide scraper strip and the roller is an acute angle or a right angle.

5. The powder spreading device for selective laser sintering according to claim 4, characterized in that: Taking the direction of the powder spreading device as the front, when spreading the powder, the horizontal position of the guide scraper in the front guide mechanism is equal to the horizontal position of the lowest point of the roller, and the horizontal position of the guide scraper in the rear guide mechanism is 0.5-5mm higher than the lowest point of the roller.

6. A forming device for selective laser sintering, characterized in that: A powder spreading device for selective laser sintering comprising the powder spreading device for selective laser sintering as described in any one of claims 1 to 5.

7. A forming method for selective laser sintering, implemented by the forming device according to claim 6, characterized in that: The steps include: Step 1: Spread a layer of polymer composite powder with different orientations. The horizontal position of the guide scraper on one side of the roller is equal to the horizontal position of the lowest point of the roller through the guide conversion mechanism. The guide scraper on one side of the roller arranges the powder material along its moving direction. The roller fills the powder surface dents caused by the guide scraper in front. After the powder is spread, laser sintering is performed. Step 2: After sintering is completed, powder is spread again. At this time, the powder spreading device moves back, and the horizontal position of the guide scraper on the other side of the drum is equal to the horizontal position of the lowest point of the drum through the guide conversion mechanism. The guide scraper is used to arrange the powder spreading material along its moving direction, and the drum fills the powder surface dents caused by the guide scraper. After powder spreading, laser sintering is performed; Step 3: before the powder spreading action in step 1 and / or step 2 begins, the guide motor is turned on to drive the motor gear to rotate. At the same time, there is a transmission relationship between the scraper gear and the guide rack, thereby driving the guide scraper connecting rod and the guide scraper to rotate, changing the angle of the guide scraper. When the angle is rotated to the required angle, the guide motor stops working; Step 4: Repeat steps 1 to 3 until all sintering layers are sintered to obtain a sample.

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