Powder 3D printer and printing method thereof

Abstract

According to the powder 3D printer and the printing method thereof, when a powder distributor is located at a first parking position or a second parking position, the lower surface of the powder distributor is lower than the upper surface of an uppermost powder layer located on a current printing platform, and the powder distributor descends by a certain height; the spray head assembly and the powder distributor do not interfere with each other in space; two energy sources are arranged in front of and behind the spray head assembly respectively, and the corresponding powder bin and the powder conveying device are arranged on the two sides of the printing platform, so that two-way powder laying and two-way printing are achieved.

Description

Technical Field

[0001] The present invention relates to the field of additive manufacturing, and in particular to a powder 3D printer. Background Art

[0002] High-speed sintering (HSS) uses an inkjet print head to distribute special ink reagents on a polymer or other powder layer according to a specific slicing pattern, and uses infrared heating technology to sinter polymer or other powder layer by layer to achieve 3D printing. Currently, the printing speed of powder 3D printers on the market is relatively slow, and most of them cannot spread powder in both directions or print in both directions. How to increase the printing speed is a problem to be optimized. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a powder 3D printer and a printing method thereof, which can not only perform bidirectional printing and bidirectional powder spreading, but also can print while spreading powder, thereby improving the printing speed.

[0004] The present invention adopts the following technical solutions:

[0005] A powder 3D printer comprises a nozzle assembly, a powder dispenser, an energy source and a printing platform, wherein the powder dispenser is used to lay powder layers on the printing platform layer by layer, the nozzle assembly is used to selectively dispense reagents to the powder layers, and the energy source is used to apply energy to the powder layers, and is characterized in that: the nozzle assembly and the energy source can move bidirectionally above the printing platform along a first axis, the powder dispenser 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, the powder dispenser has a first parking position and a second parking position, and 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.

[0006] Further, the first parking position and the second parking position are respectively located at two sides of the printing platform that are arranged opposite to each other along the second axis direction.

[0007] Furthermore, there are at least two energy sources, which are respectively arranged on opposite sides of the nozzle assembly along the first axis. An energy source is arranged at the front and rear of the nozzle assembly, and when the nozzle assembly moves along the first axis, the first energy source at the rear thereof starts to work and sinter, and when the nozzle assembly moves in the opposite direction along the first axis, the second energy source at the rear thereof starts to work and sinter, thereby realizing bidirectional printing and sintering.

[0008] Furthermore, the powder distributor is a leveling roller, and in the first parking position or the second parking position, the lower surface of the leveling roller is lower than the upper surface of the uppermost powder layer on the current printing platform, and 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 on the current printing platform. The leveling surface of the leveling roller is flush with the powder layer when spreading the powder, and after spreading the powder, the leveling roller is lowered to a certain height, so that its lower surface 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, so as not to interfere with the movement of the upper nozzle assembly.

[0009] Furthermore, the powder 3D printer further comprises a first powder bin and a second powder bin arranged on both 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 providing two powder bins and providing parking positions corresponding to the powder dispensers near the powder bins, bidirectional powder spreading is achieved.

[0010] Further, the energy source is used to sinter and solidify the powder sprayed with the 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. The powder sprayed with the infrared radiation absorber can be quickly sintered and solidified under the radiation of the infrared or near-infrared light source, and the powder sprayed with the ultraviolet radiation absorber can be quickly sintered and solidified under the radiation of the ultraviolet or near-ultraviolet light source.

[0011] Furthermore, the powder 3D printer also includes a first slide movable along a first axis and a second slide movable along a second axis, the nozzle assembly and the energy source are mounted on the first slide, and the powder dispenser is mounted on the second slide.

[0012] Furthermore, 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; a third energy source is also provided on the top of the powder 3D printer 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 comprises the following steps:

[0014] (a) The powder in the first powder bin is transported to the top thereof to form a powder pile, the powder dispenser moves upward from the first parking position to the front of the powder pile and pushes the powder pile toward the printing platform along the second axis direction to lay a powder layer, and after the powder layer is laid, the powder dispenser moves downward to the second parking position; when the powder dispenser moves to the point where a whole powder layer or a partial powder layer in a whole layer has been laid, the nozzle assembly moves from the first position along the first axis direction to the second position while selectively spraying a reagent onto the laid powder layer, and an energy source located behind the movement direction of the nozzle assembly simultaneously applies energy to the laid powder layer to sinter the powder sprayed with the reagent, thereby completing the printing of the current powder layer and lowering the printing platform to a set layer height;

[0015] (b) The powder in the second powder bin is transported to the top thereof to form a powder pile, the powder dispenser moves upward from the second parking position to the front of the powder pile and pushes the powder pile toward the printing platform in the opposite direction along the second axis to lay another powder layer, and after the laying of the powder layer is completed, the powder dispenser moves downward to the first parking position; when the powder dispenser moves to the point where a whole powder layer or a partial powder layer in a whole layer has been laid, the nozzle assembly moves from the second position to the first position in the opposite direction of the first axis while selectively spraying a reagent onto the laid powder layer, and an energy source located behind the movement direction of the nozzle assembly simultaneously applies energy to the laid powder layer to sinter the powder sprayed with the reagent, thereby completing the printing of the current powder layer and lowering the printing platform to a set layer height;

[0016] (c) Repeat steps (a) to (b) until the 3D object is printed.

[0017] Furthermore, when the second axis is parallel to or coincides with the first axis, when the powder dispenser moves to the point where a partial powder layer of a whole layer has been laid, the nozzle assembly selectively sprays reagents to the laid partial powder layer along the movement direction of the powder dispenser, and the energy source located behind the movement direction of the nozzle assembly simultaneously applies energy to the laid partial powder layer to sinter the powder sprayed with the reagents. Printing while laying powder can greatly increase the printing speed.

[0018] Furthermore, before step (a), a powder layer of a certain thickness is pre-laid on the printing platform, and the third energy source is turned on for preheating. Usually, a certain thickness of powder layer, such as 20 mm, needs to be pre-laid on the printing platform, and the powder layer is preheated.

[0019] Compared with the prior art, the present invention has the following advantages: 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, and the powder dispenser drops to a certain height, so that the nozzle assembly and the powder dispenser do not interfere with each other in space; by arranging an energy source in front and behind the nozzle assembly, and arranging corresponding powder bins and powder conveying devices on both sides of the printing platform, bidirectional powder laying and bidirectional printing can be achieved. Compared with the orthogonal slide structure, the nozzle assembly can only start printing after the powder dispenser has laid a whole layer of powder. When the second axis is parallel to or coincides with the first axis, the present invention can also print while laying powder. After the powder dispenser lays a part of the powder layer, the nozzle assembly and the energy source can start working, which greatly improves the printing speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of the powder 3D printer of Example 1 from a front view;

[0021] Figure 2 This is a schematic diagram of the structure of the powder 3D printer of Example 1 from a top view (the first slide is not shown);

[0022] Figure 3 This is a schematic diagram of the motion trajectory of the powder dispenser of Example 1;

[0023] Figure 4 is a flow chart of the printing method of embodiment 1;

[0024] Figure 5 This is a schematic diagram of the structure of the powder 3D printer of Example 2 from a top view (the first slide is not shown). DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of the technical solution of the present invention, a detailed description is given below in conjunction with the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] See also Figure 1-Figure 3, which is a schematic diagram of the structure of a powder 3D printer of the present invention. The powder 3D printer 100 includes a nozzle assembly 1, a powder dispenser 2, an energy source 3 and a printing platform 4. The printing platform 4 is provided with a lifting mechanism, and the type of the lifting mechanism is not limited. The powder dispenser 2 is used to lay the powder layer on the printing platform 4 layer by layer, which can be achieved 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, and includes a plurality of inkjet print heads. The energy source 3 is used to apply energy to the powder layer. The energy source 3 includes 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. For the convenience of distinguishing, they are named as the first energy source 31 and the second energy source 32. The first energy source 31 and the second energy source 32 are fixed to the first slide 7 together with the nozzle assembly 1. The first slide 7 can move bidirectionally above the printing platform 4 along the 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 along the direction perpendicular to the first axis, and the length direction of the printing platform 4 refers to the platform size 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, the reagent injection and energy radiation can be performed within the entire width of the printing platform 4, covering a large area and improving the printing speed.

[0028] The powder dispenser 2 is disposed on the second carriage 8, and the second carriage 8 can move bidirectionally along a second axis parallel to or coincident with the first axis. The powder dispenser 2 can move bidirectionally along the second axis above the printing platform 4 to lay powder layers layer by layer. The distribution range of the powder dispenser 2 is also greater than the width of the printing platform 4, so that the powder dispenser 2 can lay powder over the entire width of the printing platform 4 when sliding over the printing platform 4.

[0029] The powder 3D printer 100 further includes a first powder bin 9 and a second powder bin 10 disposed oppositely on both sides of the printing platform 4. The first powder bin 9 and the second powder bin 10 are disposed close to the printing platform 4 along the second axis. A powder conveying device is disposed in each powder bin for conveying powder to the top of the corresponding powder bin.

[0030] The powder dispenser 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 dispenser 2 is located at the first parking position 11 or the second parking position 12, the lower surface of the powder dispenser 2 is lower than the upper surface of the uppermost powder layer located on the current printing platform 4. Specifically, in the present embodiment, the powder dispenser 2 is a leveling roller, and the leveling roller can be arranged on a leveling roller bracket, and the leveling roller bracket is fixed to the second slide 8. In the first parking position 11 or the second parking position 12, the lower surface 18 of the leveling roller is lower than the upper surface of the uppermost powder layer 17 located on the current printing platform, and more preferably, the upper surface 19 of the leveling roller is also lower than the upper surface of the uppermost powder layer 17 of the current printing platform or is substantially flush with it. See. Figure 1 and Figure 3 , is a schematic diagram of the movement trajectory of the powder dispenser 2. When printing, the powder dispenser 2 is lifted up from the first parking position 11 which is lower than the current powder layer of the printing platform 4 by a certain height and moves to a position slightly higher than the current powder layer of the printing platform 4 (one layer higher). The leveling roller levels the powder and makes it flush with the powder layer when spreading the powder, and moves horizontally along the second axis, crosses the entire printing platform 4, and then moves downward to a certain height and enters the second parking position 12. 17 is the current powder layer after leveling. This design makes the nozzle assembly 1 and the powder dispenser 2 not interfere with each other in space; by arranging an energy source before and after the nozzle assembly 2, and arranging corresponding powder bins and powder conveying devices on both sides of the printing platform 4, bidirectional powder spreading and bidirectional printing can be achieved.

[0031] There is a cross-printing method currently on the market, where the inkjet print head moves with the infrared lamp, and the powder dispenser used to lay the powder layer is perpendicular to the movement direction of the inkjet print head. After the powder dispenser has finished laying the powder, the inkjet print head starts printing and the infrared lamp applies energy for sintering, thus achieving two-way powder laying and two-way printing. However, this technology has certain shortcomings. Due to spatial interference, the inkjet print head can only start printing after the powder dispenser has laid a whole layer of powder, which affects the improvement of printing speed. Compared with the orthogonal slide structure, the present invention can also print while laying powder. After the powder dispenser 2 lays a part of the powder layer, the nozzle assembly 1 and the energy source 3 can start working, which greatly improves the printing speed and can save 30%-40% of the printing time.

[0032] In order to preheat the powder of the powder 3D printer and adjust the temperature in time, the top of the powder 3D printer is still provided with a third energy source 13. In addition, two overflow powder troughs are provided in the length direction of the printing platform 4 for recycling excess powder.

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

[0034] (1) A powder layer of a certain thickness 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, and the powder dispenser 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. After the laying of the powder layer is completed, the powder dispenser 2 moves downward into the second parking position 12; when the powder dispenser 2 moves to the point where a whole layer of powder or a partial layer of powder in a whole layer has been laid, the nozzle assembly 1 moves from the first position 15 to the second position 16 along the first axis direction while selectively spraying a reagent onto the laid powder layer, and the first energy source 31 simultaneously applies energy to the laid powder layer to sinter the powder sprayed with the reagent, thereby completing the printing of the current powder layer and lowering the printing platform 4 to 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, and the powder dispenser 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 in the opposite direction along the second axis to lay another powder layer. After the laying of the powder layer is completed, the powder dispenser 2 moves downward into the first parking position 11; when the powder dispenser 11 moves to the point where a whole layer of powder or a partial layer of powder in a whole layer has been laid, the nozzle assembly 1 moves from the second position 16 to the first position 15 in the opposite direction along the first axis while selectively spraying a reagent onto the laid powder layer, and the second energy source 32 simultaneously applies energy to the laid powder layer to sinter the powder sprayed with the reagent, completing the printing of the current powder layer and lowering the printing platform 4 to the set layer height;

[0037] (4) Repeat steps (2) to (3) until the printing of the 3D object is completed.

[0038] Preferably, the printing method recommends that when the powder dispenser 2 moves to the point where a partial powder layer of a whole layer has been laid, the nozzle assembly 1 selectively sprays the reagent to the laid partial powder layer along the movement direction of the powder dispenser, and the energy source 3 located behind the movement direction of the nozzle assembly simultaneously applies energy to the laid partial powder layer to sinter the powder sprayed with the reagent. Compared with spraying and sintering the reagent after laying the whole powder layer, spraying and sintering the reagent at the same time after laying the partial powder layer can greatly increase the printing speed.

[0039] Example 2

[0040] Compared with Example 1, the difference of this embodiment 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 both sides of the printing platform 4 along the second axis, 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 overflow powder groove 14 is arranged in the width direction of the printing platform 4. The distribution range of the powder dispenser 2 is greater than the length of the printing platform, and the rest is the same as Example 1.

[0041] The corresponding printing method is as follows:

[0042] (1) A powder layer of a certain thickness is first 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 thereof to form a powder pile, and the powder dispenser 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. After the laying of the powder layer is completed, the powder dispenser 2 moves downward to the second parking position 12; when the powder dispenser 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 a reagent onto the laid powder layer, and the first energy source 31 simultaneously applies energy to the laid powder layer to sinter the powder sprayed with the reagent, completing the printing of the current powder layer and lowering the printing platform 4 to a set layer height;

[0044] (3) The powder conveying device conveys the powder in the second powder bin 10 to the top thereof to form a powder pile, and the powder dispenser 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 in the opposite direction along the second axis to lay another powder layer. After the laying of the powder layer is completed, the powder dispenser 2 moves downward into the first parking position 11; when the powder dispenser 2 enters the first parking position 11, the nozzle assembly 1 moves from the second position 16 to the first position 15 in the opposite direction of the first axis while selectively spraying a reagent onto the laid powder layer, and the second energy source 32 simultaneously applies energy to the laid powder layer to sinter the powder sprayed with the reagent, completing the printing of the current powder layer and lowering the printing platform to a set layer height;

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

[0046] Compared with the preferred printing method of Example 1, which simultaneously performs reagent spraying and sintering after laying a local powder layer, the orthogonal first and second slides have a relatively slow printing speed, and cannot perform sintering before the powder laying is completed, otherwise the local powder will not be able to spray reagents and sinter normally due to the obstruction of the powder dispenser 2. However, bidirectional powder laying and bidirectional printing can also be achieved, which has certain advantages over conventional unidirectional powder laying and unidirectional printing.

[0047] The above are only preferred embodiments of the present invention. The protection scope of the present invention shall be based on the scope defined by the claims. Several improvements and modifications made by those skilled in the art without departing from the spirit and scope of the present invention should also be regarded as the protection scope of the present invention.

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 a powder layer on the printing platform layer by layer, the nozzle assembly is used to selectively distribute a reagent 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, and the powder dispenser can move bidirectionally above the printing platform along a second axis to lay the powder layer, the second axis is parallel to, coincident with, or orthogonal to the first axis, and 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 according to claim 1, characterized in that: The first parking position and the second parking position are respectively located on two sides of the printing platform that are relatively arranged along the second axis direction; there are at least two energy sources, which are respectively arranged on two opposite sides of the nozzle assembly along the first axis direction.

3. The powder 3D printer according to claim 1, characterized in that: The powder dispenser is a leveling roller. In the first parking position or the second parking position, the lower surface of the leveling roller is lower than the upper surface of the topmost powder layer on 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 topmost powder layer on the current printing platform.

4. The powder 3D printer according to claim 3, characterized in that: The powder 3D printer also includes a first powder bin and a second powder bin relatively arranged on both 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 a side of the first powder bin away from the printing platform, and the second parking position is located on a side of the second powder bin away from the printing platform.

5. The powder 3D printer according to 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 according to claim 3, characterized in that: The powder 3D printer further comprises a first slide movable along a first axis and a second slide movable along a second axis, the nozzle assembly and the energy source are mounted on the first slide, and the powder dispenser is mounted on the second slide.

7. The powder 3D printer according to claim 4, characterized in that: 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; a third energy source is also provided on the top of the powder 3D printer for preheating the powder and adjusting the temperature; and the printing platform is provided with a lifting mechanism.

8. A printing method of a powder 3D printer as claimed in any one of claims 1 to 7, characterized in that The following steps are involved: (a) The powder in the first powder bin is transported to the top thereof to form a powder pile, the powder dispenser moves upward from the first parking position to the front of the powder pile and pushes the powder pile toward the printing platform along the second axis direction to lay a powder layer, and after the powder layer is laid, the powder dispenser moves downward to the second parking position; when the powder dispenser moves to the point where a whole powder layer or a partial powder layer in a whole layer has been laid, the nozzle assembly moves from the first position along the first axis direction to the second position while selectively spraying a reagent onto the laid powder layer, and an energy source located behind the movement direction of the nozzle assembly simultaneously applies energy to the laid powder layer to sinter the powder sprayed with the reagent, thereby completing the printing of the current powder layer; (b) conveying the powder in the second powder bin to the top thereof to form a powder pile, the powder dispenser moves upward from the second parking position to the front of the powder pile and pushes the powder pile toward the printing platform along the second axis in the opposite direction to lay another powder layer, and after the laying of the powder layer is completed, the powder dispenser moves downward to the first parking position; when the powder dispenser moves to the point where a whole powder layer or a partial powder layer in a whole layer has been laid, the nozzle assembly moves from the second position along the first axis in the opposite direction to the first position while selectively spraying a reagent onto the laid powder layer, and an energy source located behind the movement direction of the nozzle assembly simultaneously applies energy to the laid powder layer to sinter the powder sprayed with the reagent, thereby completing the printing of the current powder layer; (c) Repeat steps (a) to (b) until the 3D object is printed.

9. The printing method of the powder 3D printer according to claim 8, characterized in that: When the second axis is parallel to or coincides with the first axis, when the powder dispenser moves to complete the laying of a partial powder layer in a whole layer, the nozzle assembly selectively sprays reagents toward the laid partial powder layer along the movement direction of the powder dispenser, and the energy source located behind the movement direction of the nozzle assembly simultaneously applies energy to the laid partial powder layer to sinter the powder sprayed with the reagent.

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

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