A laser sintering 3D printer and a printing method thereof

Abstract

The application provides a laser sintering 3D printer and a printing method thereof. The laser sintering 3D printer adopts a forming cylinder which is transversely axially rotated and vertically penetrated, two quartz glass plate workbenches are arranged, the powder compaction problem of the powder layer is effectively solved through the downward pressing of the workbenches and the self-weight of the powder, and a bidirectional progressive mode from the center of the powder layer to the outside is adopted, so that the powder is laid on the other powder layer in the reverse direction while the powder layer is sintered, and the workpiece forming efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of additive manufacturing, and particularly relates to a laser sintering 3D printer and a printing method thereof. BACKGROUND

[0002] The SLS technology is a technology for forming a solid by completely melting a powder under the thermal action of a laser beam and solidifying the powder after cooling. Under the action of high laser energy density, the powder is completely melted, and solid forming can be achieved after cooling. The SLS technology is a rapid prototyping technology for forming a three-dimensional entity by layer-by-layer accumulation through this process.

[0003] One of the factors affecting the quality of the formed workpiece is the compaction degree of the powder layer, and low compaction degree will cause large voids in the workpiece after sintering, reducing the quality of the workpiece.

[0004] To solve the above problems, the Chinese utility model patent with publication number CN204820356U discloses a powder laying and compacting device. The utility model adopts the mode of setting a vibration pressing plate, which is lowered to contact the powder layer and vibrates for a certain time to compact the powder, and then is raised. The utility model has a certain effect on the compaction of the powder layer, but the powder will be loosened after the vibration pressing plate is raised, and the mode of the vibration pressing plate will reduce the efficiency of workpiece forming.

[0005] To solve the above problems, the Chinese utility model patent with publication number CN204820356U discloses a powder laying and compacting device. The utility model adopts the mode of setting a vibration pressing plate, which is lowered to contact the powder layer and vibrates for a certain time to compact the powder, and then is raised. The utility model has a certain effect on the compaction of the powder layer, but the powder will be loosened after the vibration pressing plate is raised, and the mode of the vibration pressing plate will reduce the efficiency of workpiece forming.

[0006] In addition to the above problems, the conventional laser sintering forming device adopts a one-way progressive mode of powder layer, i.e. laying a layer of powder and then sintering a layer, which is low in efficiency and causes long forming time of the workpiece. SUMMARY

[0007] The present application aims at the deficiencies of the prior art, and provides a laser sintering 3D printer and a printing method thereof. The forming cylinder is rotated horizontally, and double worktables are arranged, which effectively solve the problem of powder layer compaction, and the sintering mode of bidirectional progression along the center is adopted, i.e. laying powder on the reverse layer while sintering the powder layer, which improves the efficiency of workpiece forming.

[0008] The specific technical scheme of the present application is:

[0009] A laser sintering 3D printer comprises a powder spreading device and a laser device; further comprising an upper and lower through forming cylinder; the opposite centers of the outer wall of the forming cylinder are fixedly connected with one end of a rotating mechanism; the other end of the rotating mechanism is fixedly connected with the inner wall of a forming chamber; the forming cylinder is fixedly connected with a support; two worktables made of quartz glass plates are arranged in the forming cylinder in an upper and lower position; the worktables are divided into an upper worktable and a lower worktable according to the position state; the edges of the upper surface of the upper worktable and the lower surface of the lower worktable are fixedly connected with one end of an upper telescopic mechanism and one end of a lower telescopic mechanism respectively; the other end of the upper telescopic mechanism and the other end of the lower telescopic mechanism are fixedly connected with a support respectively; at least one laser device is arranged below the forming cylinder; the laser device is fixedly connected with a lifting mechanism.

[0010] Preferably, the powder spreading device is an electric screen powder spreading device or a powder spraying head powder spreading device.

[0011] Preferably, the rotating mechanism is a stepping motor, a servo motor or a rotary air cylinder.

[0012] Preferably, the upper telescopic mechanism and the lower telescopic mechanism are both ball screw pairs or air cylinders.

[0013] Preferably, the lifting mechanism is a ball screw pair or an air cylinder.

[0014] Further, the fixing connection between the forming cylinder and the support is that the upper and lower end surfaces of the side wall of the forming cylinder are respectively screw-connected with a support.

[0015] Further, a sealing element is arranged around the side surface of the worktable to prevent powder from leaking out.

[0016] Preferably, the sealing element is a felt, which has a good sealing effect.

[0017] The printing method of the laser sintering 3D printer of the present application is as follows:

[0018] First step: the axis of the rotating mechanism penetrates the contact surface of the upper worktable and the lower worktable; the laser device is set at a given sintering distance from the contact surface; the laser device performs sintering of the cross-sectional information;

[0019] Second step: the upper telescopic mechanism drives the upper worktable to rise, until the height between the upper worktable and the forming cylinder is greater than the height of the powder spreading device;

[0020] Third step: the powder spreading device is moved from the side of the forming cylinder to above the forming cylinder, and then is lowered into the forming cylinder for powder spreading; after the powder spreading is completed, the powder spreading device is raised and moved back to the original position;

[0021] Fourth step: the upper telescopic mechanism drives the upper worktable to descend to the surface of the powder layer;

[0022] Fifth step: the rotation mechanism drives the forming cylinder to rotate 180 degrees forward or reversely; at this time, the upper workbench serves as the lower workbench, and the lower workbench serves as the upper workbench;

[0023] Sixth step: the laser device is turned on, and the laser passes through the lower workbench to sinter the powder; after the laser sintering is completed, the laser device is turned off;

[0024] Seventh step: while the laser sintering in the sixth step is being performed, the second step to the fourth step are repeated; after the laser sintering in the sixth step and the repeated operation are completed, the fifth step to the sixth step are executed.

[0025] Eighth step: the lifting mechanism drives the laser device to descend by one powder layer height.

[0026] The second step to the eighth step are repeated until the workpiece sintering is completed.

[0027] The present application has the following beneficial effects:

[0028] The present application provides a laser sintering 3D printer and a printing method thereof, adopts a forming cylinder which is transversely axially rotated and penetrates upward and downward, sets two quartz glass plate workbenches, effectively solves the powder compaction problem of the powder layer through the downward pressing of the workbench and the self-weight effect of the powder, and adopts a bidirectional progressive sintering mode along the center to the outside, so that the powder is laid on the other layer in the reverse direction while the powder layer is sintered, thereby improving the workpiece forming efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a partial section schematic view of the embodiment 1 of the present application.

[0030] Figure 2 It is a forming cylinder schematic view of the embodiment 1 of the present application.

[0031] Figure 3 It is a workbench schematic view of the embodiment 1 of the present application.

[0032] Figure 4 It is a partial section schematic view of the embodiment 2 of the present application.

[0033] The structures corresponding to the numbers in the figure are as follows:

[0034] 1. powder laying device 2. laser device 3. forming cylinder 4. rotation mechanism 5. forming chamber inner wall 6. support 7. workbench 9. lifting mechanism 10. sealing element 21. laser device one 22. laser device two 71. upper workbench 72. lower workbench 81. upper telescopic mechanism 82. lower telescopic mechanism 91. lifting mechanism one 92. lifting mechanism two DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0036] Embodiment 1, reference Figures 1 to 3 .

[0037] A laser sintering 3D printer comprises a powder spreading device 1 and a laser device 2; the powder spreading device 1 is preferably a motorized sieve powder spreading or a powder spraying head; further comprising an upper and lower through forming cylinder 3; the opposite centers of the outer wall of the forming cylinder 3 are respectively screw-connected to one end of a rotating mechanism 4; the rotating mechanism 4 is preferably a stepper motor, a servo motor or a rotary cylinder; the other end of the rotating mechanism 4 is screw-connected to an inner wall 5 of a forming chamber; one bracket 6 is screw-connected to the upper and lower end surfaces of one side wall of the forming cylinder 3; the forming cylinder 3 is provided with two worktables 7 made of quartz glass plates in upper and lower positions; the worktables 7 are divided into an upper worktable 71 and a lower worktable 72 according to the position state; the opposite edges of the upper surface of the upper worktable 71 and the lower surface of the lower worktable 72 are respectively screw-connected to one end of an upper telescopic mechanism 81 and one end of a lower telescopic mechanism 82; the other end of the upper telescopic mechanism 81 and the other end of the lower telescopic mechanism 82 are respectively screw-connected to one bracket 6; the upper telescopic mechanism 81 and the lower telescopic mechanism 82 are preferably ball screw pairs or cylinders; a laser device 2 is arranged below the forming cylinder 3; the laser device 2 is screw-connected to a lifting mechanism 9; the lifting mechanism 9 is preferably a ball screw pair or a cylinder; a sealing element 10 is arranged around one side of the worktable 7 to prevent powder from leaking out; the sealing element 10 is a felt, which has good sealing effect.

[0038] The printing method of the laser sintering 3D printer of embodiment 1 is implemented as follows:

[0039] First step: the central axis of the rotating mechanism 4 penetrates the contact surface of the upper worktable 71 and the lower worktable 72; the laser device 2 is arranged at a given sintering distance from the contact surface; the laser device 2 performs bidirectional sintering of cross-sectional information;

[0040] Second step: the upper telescopic mechanism 81 drives the upper worktable 71 to rise, so that the height between the upper worktable 71 and the forming cylinder 3 is greater than the height of the powder spreading device 1;

[0041] Third step: the powder spreading device 1 moves from the side of the forming cylinder 3 to above the forming cylinder 3, and then descends into the forming cylinder 3 for powder spreading; after the powder spreading is completed, the powder spreading device 1 rises and moves back to the original position;

[0042] Fourth step: the upper telescopic mechanism 81 drives the upper worktable 71 to descend to the surface of the powder layer;

[0043] Fifth step: the rotation mechanism 4 drives the forming cylinder 3 to rotate 180 degrees forward or backward; at this time, the upper workbench 71 acts as the lower workbench, and the lower workbench 72 acts as the upper workbench;

[0044] Sixth step: turn on the laser device 2, and sinter the powder through the lower workbench; after the laser sintering is completed, the laser device 2 is turned off;

[0045] Seventh step: while performing the sixth step of laser sintering, repeat the second step to the fourth step; after the sixth step of laser sintering and the repeated operation are completed, execute the fifth step to the sixth step.

[0046] Eighth step: the lifting mechanism 9 drives the laser device 2 to descend by one powder layer height.

[0047] Repeat the second step to the eighth step until the workpiece sintering is completed.

[0048] Example 2, reference Figure 4 . The difference from example 1 is that the forming cylinder 3 is provided with laser device one 21 and laser device two 22, which are respectively screwed with lifting mechanism one 91 and lifting mechanism two 92. Example 2 is the same as example 1.

[0049] When the printing method of the laser sintering 3D printer in example 2 is implemented:

[0050] First step: the axis in the rotation mechanism 4 penetrates the contact surface of the upper workbench 71 and the lower workbench 72; the laser device one 21 and the laser device two 22 are set with a given sintering distance from the contact surface; the laser device one 21 and the laser device two 22 respectively perform reverse one-way sintering section information;

[0051] Second step: the upper telescopic mechanism 81 drives the upper workbench 71 to rise, so that the height between the upper workbench 71 and the forming cylinder 3 is greater than the height of the powder laying device 1;

[0052] Third step: the powder laying device 1 moves from the side of the forming cylinder 3 to above the forming cylinder 3, and then descends into the forming cylinder 3 for powder laying; after the powder laying is completed, the powder laying device 1 rises and moves back to the original position;

[0053] Fourth step: the upper telescopic mechanism 81 drives the upper workbench 71 to descend to the powder layer surface;

[0054] Fifth step: the rotation mechanism 4 drives the forming cylinder 3 to rotate 180 degrees forward or backward; at this time, the upper workbench 71 acts as the lower workbench, and the lower workbench 72 acts as the upper workbench;

[0055] Sixth step: turn on the laser device one 21, and sinter the powder through the lower workbench; after the laser sintering is completed, the laser device one 21 is turned off; while the laser sintering is performed, repeat the second step to the fourth step;

[0056] Step 7: repeat Step 5; meanwhile, the lifting mechanism 91 lowers the laser device 21 by one powder layer height;

[0057] Step 8: turn on the laser device 22, and the laser passes through the lower worktable 72 to sinter the powder; after the laser sintering is completed, the laser device 22 is turned off; meanwhile, Steps 2 to 4 are repeated;

[0058] Step 9: repeat Step 5; meanwhile, the lifting mechanism 92 lowers the laser device 22 by one powder layer height;

[0059] Steps 6 to 9 are repeated until the workpiece sintering is completed.

[0060] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it. The present application is not limited to the exact structure described above and shown in the drawings, and the specific implementation of the present application should not be considered as being limited to the above description. Any change and modification made by those skilled in the art without departing from the concept of the present application should be considered as falling within the protection scope of the present application.

Claims

1. A printing method for a laser sintering 3D printer, wherein, The printer includes a powder spreading device (1) and a laser device (2); it also includes a forming cylinder (3) that runs vertically through the cylinder; one end of a rotating mechanism (4) is fixedly connected to the center of the outer wall of the forming cylinder (3); the other end of the rotating mechanism (4) is fixedly connected to the inner wall of the forming cylinder (5); the forming cylinder (3) is fixedly connected to a bracket (6); the forming cylinder (3) is provided with two worktables (7) made of quartz glass plates that are vertically opposite to each other; the worktables (7) are divided into an upper worktable (71) and a lower worktable (72) according to their position; the upper surface of the upper worktable (71) and the lower surface of the lower worktable (72) are fixedly connected to the edges of the upper and lower surfaces of the lower worktable (72) respectively; the other end of the upper and lower telescopic mechanisms (81) and the other end of the lower telescopic mechanism (82) are fixedly connected to the bracket (6); at least one laser device (2) is provided below the forming cylinder (3); the laser device (2) is fixedly connected to a lifting mechanism (9); the printing method is characterized by the following steps: Step 1: The central axis of the rotating mechanism (4) is on the same horizontal plane as the contact surfaces of the upper worktable (71) and the lower worktable (72); the laser device (2) is set with a given sintering distance from the contact surfaces; the laser device (2) executes the sintering cross-section information; Step 2: The upper telescopic mechanism (81) drives the upper worktable (71) to rise until the height between the upper worktable (71) and the forming cylinder (3) is greater than the height of the powder spreading device (1); Step 3: The powder spreading device (1) moves from the side of the forming cylinder (3) to above the forming cylinder (3), and descends into the forming cylinder (3) to spread powder; after the powder spreading is completed, the powder spreading device (1) rises and moves back to its original position; Step 4: The upper telescopic mechanism (81) drives the upper worktable (71) to descend to the surface of the powder layer; Step 5: The rotating mechanism (4) drives the forming cylinder (3) to rotate 180 degrees in the forward or reverse direction; at this time, the upper worktable (71) becomes the lower worktable, and the lower worktable (72) becomes the upper worktable; Step 6: Turn on the laser device (2). The laser passes through the lower worktable to sinter the powder. After the laser sintering is completed, the laser device (2) is turned off. Step 7: While performing the laser sintering in step 6, repeat steps 2 to 4; after the laser sintering in step 6 and the repeated operation are completed, proceed to steps 5 and 6. Step 8: The lifting mechanism (9) drives the laser device (2) to descend by one powder layer height; Repeat steps two through eight until the workpiece is sintered.

2. The printing method of a laser sintering 3D printer according to claim 1, characterized in that: The powder spreading device (1) is an electric sieve for spreading powder or a powder spraying head for spreading powder.

3. The printing method of a laser sintering 3D printer according to claim 1, characterized in that: The rotating mechanism (4) is a stepper motor, a servo motor, or a rotary cylinder.

4. The printing method of a laser sintering 3D printer according to claim 1, characterized in that: Both the upper telescopic mechanism (81) and the lower telescopic mechanism (82) are ball screw pairs or cylinders.

5. The printing method of a laser sintering 3D printer according to claim 1, characterized in that: The lifting mechanism (9) is a ball screw pair or a cylinder.

6. The printing method of a laser sintering 3D printer according to claim 1, characterized in that: The molding cylinder (3) and the bracket (6) are fixedly connected by screws to the upper and lower surfaces of one side wall of the molding cylinder (3).

7. The printing method of a laser sintering 3D printer according to claim 1, characterized in that: The workbench (7) has a sealing element (10) around its side.

8. The printing method of a laser sintering 3D printer according to claim 7, characterized in that: The sealing element (10) is felt.

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