A powder 3D printer and a printing method thereof

Abstract

The application discloses a powder 3D printer and a printing method thereof. When a powder distributor is located at a first parking position or a second parking position, a lower surface of the powder distributor is lower than an upper surface of an uppermost powder layer of a current printing platform, the powder distributor is lowered by a certain height, and a nozzle assembly and the powder distributor are spatially not interfered with each other. By arranging an energy source in front of and behind the nozzle assembly and arranging corresponding powder bins and powder conveying devices on both sides of the printing platform, bidirectional powder spreading and bidirectional printing are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of additive manufacturing, in particular to a powder 3D printer. BACKGROUND

[0002] High speed sintering (HSS) is a 3D printing technology that uses inkjet printheads to dispense special ink reagents on a layer of powder such as polymer according to a specific slice pattern, and uses infrared heating technology to sinter the powder such as polymer layer by layer to realize 3D printing. The printing speed of the powder 3D printer on the market is relatively slow, and most of them cannot print bidirectionally with bidirectional powder spreading. How to improve the printing speed is a problem to be optimized. SUMMARY

[0003] To solve the above technical problems, the present application provides a powder 3D printer and a printing method thereof, which can not only print bidirectionally with bidirectional powder spreading, but also print while spreading powder, thereby improving the printing speed.

[0004] The present application adopts the following technical scheme:

[0005] A powder 3D printer, comprising a nozzle assembly, a powder distributor, an energy source and a printing platform, the powder distributor is used to lay a powder layer on the printing platform layer by layer, the nozzle assembly is used to selectively distribute reagents to the powder layer, and the energy source is used to apply energy to the powder layer, characterized in that: the nozzle assembly and the energy source can move bidirectionally above the printing platform along a first axis, the powder distributor can move bidirectionally above the printing platform along a second axis to lay the powder layer, the second axis is parallel to, coincides with or is orthogonal to the first axis, and the powder distributor has a first parking position and a second parking position, when the powder distributor is located at the first parking position or the second parking position, the lower surface of the powder distributor is lower than the upper surface of the uppermost powder layer on the printing platform.

[0006] Further, the first parking position and the second parking position are respectively located on the two sides of the printing platform along the direction of the second axis.

[0007] Further, the energy source is at least two, which are respectively arranged on the opposite sides of the nozzle assembly along the direction of the first axis. One energy source is arranged in front of and behind the nozzle assembly, when the nozzle assembly moves along the first axis, the first energy source behind the nozzle assembly works to sinter, when the nozzle assembly moves reversely along the first axis, the second energy source behind the nozzle assembly starts to work to sinter, thereby realizing bidirectional printing and sintering.

[0008] Further, the powder distributor is a leveling roller, the lower surface of the leveling roller is lower than the upper surface of the uppermost powder layer of the current printing platform in the first parking position or the second parking position, the upper surface of the leveling roller is lower than or flush with the upper surface of the uppermost powder layer of the current printing platform in the first parking position or the second parking position. The leveling surface of the leveling roller is flush with the powder layer during powder spreading, and the leveling roller is lowered by a certain height after powder spreading, so that the lower surface of the leveling roller is lower than the upper surface of the uppermost powder layer, and the upper surface is also lower than or flush with the upper surface of the uppermost powder layer, thereby not interfering with the movement of the upper nozzle assembly.

[0009] Further, the powder 3D printer further comprises a first powder bin and a second powder bin arranged opposite to the two sides of the printing platform, the first powder bin and the second powder bin are arranged close to the printing platform along the second axis direction, the first parking position is located on the side of the first powder bin away from the printing platform, and the second parking position is located on the side of the second powder bin away from the printing platform. By arranging two powder bins and parking positions of corresponding powder distributors near the powder bins, bidirectional powder spreading is realized.

[0010] Further, the energy source is used for sintering and curing the powder sprayed with the reagent, the energy source is an infrared or near-infrared light source or an ultraviolet or near-ultraviolet light source; and the reagent contains an infrared radiation absorber or an ultraviolet radiation absorber. The powder sprayed with the infrared radiation absorber can be quickly sintered and cured under the radiation of an infrared or near-infrared light source, and the powder sprayed with the ultraviolet radiation absorber can be quickly sintered and cured under the radiation of an ultraviolet or near-ultraviolet light source.

[0011] Further, the powder 3D printer further comprises a first carriage movable along the first axis and a second carriage movable along the second axis, the nozzle assembly and the energy source are installed on the first carriage, and the powder distributor is installed on the second carriage.

[0012] Further, the first powder bin and the second powder bin are respectively provided with a powder conveying device for conveying powder to the top of the corresponding powder bin; the top of the powder 3D printer is further provided with a third energy source for preheating and adjusting the temperature of the powder; and the printing platform is provided with a lifting mechanism.

[0013] A printing method of the powder 3D printer, comprising the following steps:

[0014] (a) powder in the first powder bin is delivered to the top of the first powder bin to form a powder pile, the powder distributor moves upward from the first parking position to the front of the powder pile and pushes the powder pile to the printing platform along the second axis direction to lay a powder layer, after the powder layer is laid, the powder distributor moves downward into the second parking position; when the powder distributor moves to complete a whole layer of powder layer or partial powder layer laying in a whole layer, the nozzle assembly moves from the first position to the second position along the first axis direction while selectively spraying the laid powder layer with reagents, the energy source located behind the movement direction of the nozzle assembly applies energy to the laid powder layer at the same time to sinter the powder of the sprayed reagents, the printing of the current powder layer is completed and the printing platform is lowered by a certain layer height;

[0015] (b) powder in the second powder bin is delivered to the top of the second powder bin to form a powder pile, the powder distributor moves upward from the second parking position to the front of the powder pile and pushes the powder pile to the printing platform along the second axis direction to lay another powder layer, after the powder layer is laid, the powder distributor moves downward into the first parking position; when the powder distributor moves to complete a whole layer of powder layer or partial powder layer laying in a whole layer, the nozzle assembly moves from the second position to the first position along the first axis direction while selectively spraying the laid powder layer with reagents, the energy source located behind the movement direction of the nozzle assembly applies energy to the laid powder layer at the same time to sinter the powder of the sprayed reagents, the printing of the current powder layer is completed and the printing platform is lowered by a certain layer height;

[0016] (c) repeat steps (a) to (b) until the printing of the 3D object is completed.

[0017] Further, when the powder distributor moves to complete partial powder layer laying in a whole layer, the nozzle assembly selectively sprays reagents to the laid partial powder layer along the movement direction of the powder distributor at this time, and the energy source located behind the movement direction of the nozzle assembly applies energy to the laid partial powder layer at the same time to sinter the powder of the sprayed reagents. Powder laying and printing at the same time can greatly improve the printing speed.

[0018] Further, before step (a), a certain thickness of powder layer is laid on the printing platform in advance, and the third energy source is turned on for preheating. It is usually necessary to lay a certain thickness of powder layer on the printing platform, for example, 20 mm, and preheat the powder layer.

[0019] Compared with the prior art, the present application has the following advantages: when the powder distributor is in the first parking position or the second parking position, the lower surface of the powder distributor is lower than the upper surface of the uppermost powder layer on the current printing platform, the powder distributor is lowered by a certain height, the nozzle assembly and the powder distributor are spatially not interfered with each other, one energy source is arranged in front of and behind the nozzle assembly, and corresponding powder bins and powder conveying devices are arranged on both sides of the printing platform, so that bidirectional powder laying and bidirectional printing are realized. Compared with the orthogonal carriage structure, the nozzle assembly can start printing only after the powder distributor lays a complete powder layer, and the present application can also print while laying powder when the second axis is parallel to or coincides with the first axis, the nozzle assembly and the energy source can start working after the powder distributor lays a part of the powder layer, and the printing speed is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the front view angle of the powder 3D printer of embodiment 1.

[0021] Figure 2 It is a structural schematic diagram of the top view angle of the powder 3D printer of embodiment 1 (the first carriage is not shown).

[0022] Figure 3 It is a schematic diagram of the movement trajectory of the powder distributor of embodiment 1.

[0023] Figure 4 It is a flowchart of the printing method of embodiment 1.

[0024] Figure 5 It is a structural schematic diagram of the top view angle of the powder 3D printer of embodiment 2 (the first carriage is not shown). DETAILED DESCRIPTION

[0025] In order to facilitate understanding of the technical scheme of the present application, the following will be described in detail in combination with the drawings and specific embodiments.

[0026] Embodiment 1

[0027] Reference Figures 1-3Figure 1 is a schematic diagram of a powder 3D printer according to the present application. The powder 3D printer 100 comprises a nozzle assembly 1, a powder distributor 2, an energy source 3 and a printing platform 4. The printing platform 4 is provided with a lifting mechanism, which is not limited in type. The powder distributor 2 is used to lay powder layers on the printing platform 4 layer by layer, which can be realized in the form of a leveling roller, etc. The powder 5 can be nylon powder, such as PA12, PA11, or other plastic powder, such as PP, TPU, etc. The nozzle assembly 1 is used to selectively distribute reagents to the powder layer according to the slicing pattern, which comprises a plurality of inkjet print heads. The energy source 3 is used to apply energy to the powder layer. The energy source 3 comprises at least two, which are respectively arranged on both sides of the nozzle assembly 1. The energy source 3 is an infrared or near-infrared light source. The reagent is an ink containing an infrared radiation absorber. The powder layer sprayed with the reagent can be quickly sintered and solidified under the radiation of the energy source 3 to form a sintered body 6. In order to facilitate the naming and distinction, the first energy source 31 and the second energy source 32 are fixed together with the nozzle assembly 1 on a first carriage 7, which can move bidirectionally above the printing platform 4 along a first axis. The length of the nozzle assembly 1 is greater than the width of the printing platform 4. Here, the width of the printing platform 4 is defined as the platform size in the direction perpendicular to the first axis, and the length of the printing platform 4 is defined as the platform size in the direction along the first axis. The radiation range of the energy source 3 is also greater than the width of the printing platform 4, so that when the nozzle assembly 1 and the energy source 3 slide over the printing platform, reagent spraying and energy radiation can be performed on the entire width of the printing platform 4, which has a large coverage area and improves the printing speed.

[0028] The powder distributor 2 is arranged on a second carriage 8, which can move bidirectionally along a second axis parallel or coinciding with the first axis. The powder distributor 2 can move bidirectionally above the printing platform 4 along the second axis to lay powder layers layer by layer. The distribution range of the powder distributor 2 is also greater than the width of the printing platform 4, so that when the powder distributor 2 slides over the printing platform 4, powder can be laid on the entire width of the printing platform 4.

[0029] The powder 3D printer 100 further comprises a first powder bin 9 and a second powder bin 10 arranged opposite to both sides of the printing platform 4. The first powder bin 9 and the second powder bin 10 are arranged close to the printing platform 4 along the direction of the second axis. Each powder bin is provided with a powder conveying device for conveying powder to the top of the corresponding powder bin.

[0030] The powder distributor 2 has a first parking position 11 and a second parking position 12, the first parking position 11 is located on the side of the first powder bin 9 away from the printing platform 4, and the second parking position 12 is located on the side of the second powder bin 10 away from the printing platform 4. When the powder distributor 2 is located in the first parking position 11 or the second parking position 12, the lower surface of the powder distributor 2 is lower than the upper surface of the uppermost powder layer of the current printing platform 4. Specifically, the powder distributor 2 in this embodiment is a leveling roller, which can be arranged on a leveling roller support fixed with the second slide 8. The lower surface 18 of the leveling roller in the first parking position 11 or the second parking position 12 is lower than the upper surface of the uppermost powder layer 17 of the current printing platform, and more preferably the upper surface 19 of the leveling roller is also lower than or substantially flush with the upper surface of the uppermost powder layer 17 of the current printing platform. See Figure 1 and Figure 3 Fig. 7 is a schematic diagram of the movement trajectory of the powder distributor 2, during printing, the powder distributor 2 is lifted to a position slightly higher than the powder layer of the current printing platform 4 (one layer height higher) from the first parking position 11 below the powder layer of the current printing platform 4, the leveling surface of the leveling roller levels the powder with the powder layer during powder laying, and moves horizontally along the second axis, after crossing the entire printing platform 4, it is lowered to the second parking position 12. 17 is the current powder layer after leveling. This design allows the inkjet head assembly 1 and the powder distributor 2 to be spatially independent of each other; by arranging an energy source before and after the inkjet head assembly 2, and corresponding powder bins and powder conveying devices on both sides of the printing platform 4, bidirectional powder laying and bidirectional printing are realized.

[0031] There is a cross printing method on the market, the inkjet print head moves together with the infrared lamp, the powder distributor for laying the powder layer is perpendicular to the movement direction of the inkjet print head, after the powder distributor finishes laying a layer of powder, the inkjet print head starts printing while the infrared lamp applies energy for sintering, realizing bidirectional powder laying and bidirectional printing. However, this technology has certain shortcomings, due to spatial interference, the inkjet print head can only start printing after the powder distributor lays a complete layer of powder, which affects the improvement of printing speed. Compared with the orthogonal slide structure, the present application can also lay powder and print at the same time, the inkjet head assembly 1 and the energy source 3 can start working after the powder distributor 2 lays a part of the powder layer, which greatly improves the printing speed and saves 30%-40% of the printing time.

[0032] In order to preheat and timely adjust the temperature of the powder of the powder 3D printer, a third energy source 13 is also arranged on the top of the powder 3D printer. In addition, two powder overflow grooves are arranged in the length direction of the printing platform 4 for recycling excess powder.

[0033] See Figure 4The embodiment also provides a printing method of the powder 3D printer, comprising the following steps:

[0034] (1) A certain thickness of powder layer is first laid on the printing platform 4, and the third energy source 13 is turned on for preheating. The power of the third energy source 13 can be adjusted according to the actual temperature;

[0035] (2) The powder conveying device conveys the powder in the first powder bin 9 to the top thereof to form a powder pile, the powder distributor 2 moves upward from the first parking position 11 to the front of the powder pile and pushes the powder pile toward the printing platform 4 along the second axis direction to lay a layer of powder, and after the laying of the powder layer is completed, the powder distributor 2 moves downward into the second parking position 12. When the powder distributor 2 moves to the position where the laying of a whole layer of powder or the laying of a partial layer of powder in a whole layer is completed, the nozzle assembly 1 moves from the first position 15 to the second position 16 along the first axis direction while selectively spraying the reagent to the laid powder layer, and the first energy source 31 simultaneously applies energy to the laid powder layer to sinter the powder of the sprayed reagent, the printing of the current powder layer is completed, and the printing platform 4 is lowered by a set layer height;

[0036] (3) The powder conveying device conveys the powder in the second powder bin 10 to the top thereof to form a powder pile, the powder distributor 2 moves upward from the second parking position 12 to the front of the powder pile and pushes the powder pile toward the printing platform 4 along the second axis direction to lay a layer of powder, and after the laying of the powder layer is completed, the powder distributor 2 moves downward into the first parking position 11. When the powder distributor 2 moves to the position where the laying of a whole layer of powder or the laying of a partial layer of powder in a whole layer is completed, the nozzle assembly 1 moves from the second position 16 to the first position 15 along the first axis direction while selectively spraying the reagent to the laid powder layer, and the second energy source 32 simultaneously applies energy to the laid powder layer to sinter the powder of the sprayed reagent, the printing of the current powder layer is completed, and the printing platform 4 is lowered by a set layer height;

[0037] (4) Steps (2) to (3) are repeated until the printing of the 3D object is completed.

[0038] As a preferred, the printing method recommends that when the powder distributor 2 moves to the position where the laying of a partial layer of powder in a whole layer is completed, the nozzle assembly 1 selectively sprays the reagent to the laid partial layer of powder along the moving direction of the powder distributor, and the energy source 3 located behind the moving direction of the nozzle assembly simultaneously applies energy to the laid partial layer of powder to sinter the powder of the sprayed reagent. Compared with the laying of a whole layer of powder and then the spraying and sintering of the reagent, the laying of a partial layer of powder and then the spraying and sintering of the reagent can greatly improve the printing speed.

[0039] Embodiment 2

[0040] The difference between the present embodiment and the embodiment 1 is that the first axis and the second axis are orthogonal, the first powder bin 9 and the second powder bin 10 are arranged on the two sides of the printing platform 4 along the second axis direction, the first parking position 11 is located on the side of the first powder bin 9 away from the printing platform 4, and the second parking position 12 is located on the side of the second powder bin 10 away from the printing platform 4. The powder overflow groove 14 is arranged in the width direction of the printing platform 4. The distribution range of the powder distributor 2 is greater than the length of the printing platform, and the rest is the same as the embodiment 1.

[0041] The corresponding printing method is as follows:

[0042] (1) First, a certain thickness of powder layer is laid on the printing platform 4, and the third energy source 13 is turned on for preheating.

[0043] (2) The powder conveying device conveys the powder in the first powder bin to the top to form a powder pile, the powder distributor 2 moves upward from the first parking position 11 to the front of the powder pile and pushes the powder pile to the printing platform 4 along the second axis direction to lay a layer of powder layer, after the laying of the powder layer is completed, the powder distributor 2 moves downward into the second parking position 12; when the powder distributor 2 enters the second parking position 12, the nozzle assembly 1 moves from the first position 15 to the second position 15 along the first axis direction while selectively spraying the reagent to the laid powder layer, and the first energy source 31 simultaneously applies energy to the laid powder layer to sinter the powder of the sprayed reagent, completes the printing of the current powder layer, and lowers the printing platform 4 by a certain layer height;

[0044] (3) The powder conveying device conveys the powder in the second powder bin 10 to the top to form a powder pile, the powder distributor 2 moves upward from the second parking position 12 to the front of the powder pile and pushes the powder pile to the printing platform 4 along the second axis direction to lay another layer of powder layer, after the laying of the powder layer is completed, the powder distributor 2 moves downward into the first parking position 11; when the powder distributor 2 enters the first parking position 11, the nozzle assembly 1 moves from the second position 16 to the first position 15 along the first axis direction while selectively spraying the reagent to the laid powder layer, and the second energy source 32 simultaneously applies energy to the laid powder layer to sinter the powder of the sprayed reagent, completes the printing of the current powder layer, and lowers the printing platform by a certain layer height;

[0045] (4) Repeat steps (2)-(3) until the printing of the 3D object is completed.

[0046] Compared with the preferred printing method of example 1, the printing speed of the orthogonal first carriage and second carriage design is relatively slow, and the local powder layer cannot be sintered before the powder is laid, otherwise the local powder cannot be normally sprayed with reagent and sintered due to the shielding of the powder distributor 2. However, bidirectional powder laying and bidirectional printing can also be achieved, which has certain advantages compared with the conventional unidirectional powder laying and unidirectional printing.

[0047] The above is only the preferred embodiment of the present application, and the protection scope of the present application is limited by the scope defined by the claims. Several improvements and refinements made by those skilled in the art without departing from the spirit and scope of the present application should also be considered as the protection scope of the present application.

Claims

1. A powder 3D printer, comprising a nozzle assembly, a powder dispenser, an energy source, and a printing platform, wherein the powder dispenser is used to lay powder layers onto the printing platform layer by layer, the nozzle assembly is used to selectively dispense reagents onto the powder layers, and the energy source is used to apply energy to the powder layers, characterized in that: The nozzle assembly and the energy source are bidirectionally movable above the printing platform along a first axis, and the powder dispenser is bidirectionally movable above the printing platform along a second axis to lay the powder layer. The second axis is parallel to, coincides with, or is orthogonal to the first axis. The powder dispenser has a first parking position and a second parking position. When the powder dispenser is located at the first parking position or the second parking position, the lower surface of the powder dispenser is lower than the upper surface of the uppermost powder layer located on the current printing platform.

2. The powder 3D printer as described in claim 1, characterized in that: The first parking position and the second parking position are respectively located on both sides of the printing platform that are arranged opposite each other along the second axis; the energy source is at least two, respectively arranged on both sides of the nozzle assembly along the first axis.

3. The powder 3D printer as described in claim 1, characterized in that: The powder dispenser is a leveling roller. At the first or second stopping position, the lower surface of the leveling roller is lower than the upper surface of the uppermost powder layer on the current printing platform. At the first or second stopping position, the upper surface of the leveling roller is lower than or flush with the upper surface of the uppermost powder layer on the current printing platform.

4. The powder 3D printer as described in claim 3, characterized in that: The powder 3D printer also includes a first powder chamber and a second powder chamber disposed opposite to each other on both sides of the printing platform. The first powder chamber and the second powder chamber are disposed close to the printing platform along the second axis. The first parking position is located on the side of the first powder chamber away from the printing platform, and the second parking position is located on the side of the second powder chamber away from the printing platform.

5. The powder 3D printer as described in claim 1, characterized in that: The energy source is used to sinter and solidify the powder of the sprayed reagent, and the energy source is an infrared or near-infrared light source or an ultraviolet or near-ultraviolet light source; the reagent contains an infrared radiation absorber or an ultraviolet radiation absorber.

6. The powder 3D printer as described in claim 3, characterized in that: The powder 3D printer also includes a first carriage movable along a first axis and a second carriage movable along a second axis, the nozzle assembly and the energy source being mounted on the first carriage, and the powder dispenser being mounted on the second carriage.

7. The powder 3D printer as described in claim 4, characterized in that: The first and second powder hoppers are each equipped with a powder conveying device for conveying powder to the top of the corresponding powder hopper; the top of the powder 3D printer is also equipped with a third energy source for preheating the powder and regulating its temperature; the printing platform is equipped with a lifting mechanism.

8. A printing method for a powder 3D printer as described in any one of claims 1 to 7, characterized in that... Includes the following steps: (a) The powder in the first powder chamber is conveyed to its top to form a powder pile. The powder distributor moves upward from the first parking position to the front of the powder pile and pushes the powder pile towards the printing platform along the second axis to lay a powder layer. After the powder layer is laid, the powder distributor moves downward to the second parking position. When the powder distributor moves to the point where a whole powder layer or a part of a whole powder layer has been laid, the nozzle assembly moves from the first position to the second position along the first axis and selectively sprays reagent onto the laid powder layer. The energy source located behind the nozzle assembly in the direction of movement simultaneously applies energy to the laid powder layer to sinter the sprayed reagent powder, thus completing the printing of the current powder layer. (b) The powder in the second powder chamber is conveyed to its top to form a powder pile. The powder distributor moves upward from the second parking position to the front of the powder pile and pushes the powder pile towards the printing platform in the opposite direction along the second axis to lay another powder layer. After the powder layer is laid, the powder distributor moves downward to the first parking position. When the powder distributor moves to the point where a whole powder layer or a part of a whole layer has been laid, the nozzle assembly moves from the second position to the first position in the opposite direction along the first axis while selectively spraying reagent into the laid powder layer. The energy source located behind the nozzle assembly in the direction of movement simultaneously applies energy to the laid powder layer to sinter the sprayed reagent powder, thus completing the printing of the current powder layer. (c) Repeat steps (a) to (b) until the printing of the 3D object is complete.

9. The printing method of the powder 3D printer as described in claim 8, characterized in that: When the second axis is parallel to or coincides with the first axis, when the powder distributor moves to the point where a local powder layer has been laid in a whole layer, the nozzle assembly selectively sprays reagent into the laid local powder layer along the direction of movement of the powder distributor. At the same time, the energy source located behind the direction of movement of the nozzle assembly applies energy to the laid local powder layer to sinter the powder of the sprayed reagent.

10. The printing method of the powder 3D printer as described in claim 8 or 9, characterized in that: Before step (a), a powder layer of a certain thickness is laid on the printing platform in advance, and the third energy source is turned on to preheat and adjust the power according to the temperature.

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