Pneumatic extrusion system and method of using the same

Abstract

The application provides a pneumatic extrusion system and a use method thereof. The pneumatic extrusion system is applied to a direct writing forming 3D printing operation, comprises a barrel with a cavity, a piston assembly slidingly arranged in the cavity, and a feeding port and a discharging port respectively arranged at two ends of the barrel and communicated with the cavity. The piston assembly comprises a first piston and a second piston, and a connecting rod connecting the first piston and the second piston. The piston assembly divides the cavity into a material cavity between the first piston and the discharging port, a communication cavity between the first piston and the second piston, and a gas cavity between the second piston and the feeding port. A communication part for communicating the external environment and the communication cavity is arranged on the barrel. The pneumatic extrusion system can prevent gas from entering the slurry during the slurry extrusion process, thereby avoiding the problems of slurry solid-liquid separation and pore generation, and ensuring the quality stability and process reliability of the slurry extrusion.

Description

Technical Field

[0001] This invention relates to the field of 3D printing technology, and in particular to a pneumatic extrusion system. Furthermore, this invention also relates to a method of using the pneumatic extrusion system. Background Technology

[0002] Currently, based on fused deposition modeling (FDM) technology, 3D printing technology has developed another extrusion-type printing process—slurry direct writing (DIW). The DIW process involves extruding a high-viscosity slurry into filaments through a nozzle at room temperature, and then depositing the designed structure layer by layer from point to line, and from line to surface.

[0003] The commonly used direct writing molding equipment for slurry is a pneumatic extrusion system. Since the extrusion pressure is provided by compressed gas and the piston and barrel have poor sealing, this type of extrusion system is prone to solid-liquid separation of slurry during the direct writing molding process, which leads to changes in the content of solid and liquid phases. Therefore, traditional pneumatic extrusion systems generally have the problem of unstable extrusion speed.

[0004] Furthermore, since the gas trapped in the barrel has no space to escape, it inevitably has to be extruded from the nozzle before the slurry is extruded from the nozzle. This results in air bubbles being extruded from the nozzle, causing discontinuity in the slurry. This phenomenon can not only temporarily interrupt the local printing trajectory during the extrusion process, leaving the printing trajectory without material filling, but may also damage the formed blank, causing the blank to deform or even collapse, affecting the printing quality stability and process reliability. Summary of the Invention

[0005] In view of this, the present invention aims to provide a pneumatic extrusion system that can improve the quality stability and process reliability of slurry extrusion.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A pneumatic extrusion system is used in direct-write 3D printing operations, including a barrel with a cavity and a piston assembly slidably disposed in the cavity, wherein the barrel has an inlet and an outlet communicating with the cavity at both ends.

[0008] The piston assembly includes a first piston and a second piston, and a connecting rod connecting the first piston and the second piston. The piston assembly divides the cavity into a material cavity located between the first piston and the discharge port, a communicating cavity located between the first piston and the second piston, and an air cavity located between the second piston and the inlet. The cylinder is provided with a communicating portion for communicating with the external environment and the communicating cavity.

[0009] Furthermore, the barrel is provided with a barrel cover located at the feed inlet, the air chamber is formed between the second piston and the barrel cover, and the barrel cover is provided with an air inlet pipe connected to both the air chamber and an external air source.

[0010] Furthermore, a printing nozzle is provided at the end of the material cylinder away from the material cylinder cover, and the printing nozzle is connected to the discharge port.

[0011] Furthermore, the barrel cover is screwed to the barrel.

[0012] Furthermore, a sealing ring is provided between the barrel cover and the barrel.

[0013] Furthermore, the first piston, the second piston, and the connecting rod are coaxially arranged.

[0014] Furthermore, the connecting portion includes a connecting vent hole that extends through the cylinder wall of the material cylinder.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] The pneumatic extrusion system of the present invention can connect the external environment and the connecting cavity through the connecting part when the first piston is driven to extrude the slurry by pushing the second piston. This allows the slurry to be continuously extruded only under the mechanical pushing action of the first piston. No gas enters the slurry during the slurry extrusion process, which effectively avoids the problems of solid-liquid separation and the generation of pores in the slurry. This separates the harmful effect of gas from the slurry, ensuring the quality stability and process reliability of the slurry extrusion.

[0017] Another object of the present invention is to provide a method of using a pneumatic extrusion system, the method being applied to the pneumatic extrusion system as described above, and the method comprising the following steps:

[0018] The second piston is pushed by an external air source so that when the first piston is driven by the second piston to extrude the slurry in the material chamber, it can connect the external environment with the connecting chamber through the connecting part, so that the slurry is continuously extruded only under the mechanical pushing action of the first piston.

[0019] The method of using the pneumatic extrusion system described in this invention can ensure that no gas enters the slurry during the slurry extrusion process, effectively avoiding the problems of solid-liquid separation and the generation of pores in the slurry, and ensuring the quality stability and process reliability of the slurry extrusion. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 This is a schematic diagram of the overall structure of the pneumatic extrusion system according to an embodiment of the present invention;

[0022] Explanation of reference numerals in the attached figures:

[0023] 1. Second piston; 2. First piston; 3. Connecting rod; 4. Connecting vent;

[0024] 5. Material cylinder; 51. Material chamber; 52. Connecting chamber; 53. Air chamber;

[0025] 6. Air inlet pipe; 7. Material cylinder cover; 8. Slurry; 9. Printing nozzle. Detailed Implementation

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0027] In the description of this invention, it should be noted that the use of terms such as "upper," "lower," "inner," and "outer," indicating orientation or positional relationship, is based on the orientation or positional relationship shown in the accompanying drawings and is only for the convenience of describing the invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the use of terms such as "first" and "second" is also for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] Furthermore, in the description of this invention, unless otherwise explicitly defined, the terms "installation," "connection," "joining," and "connector" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0029] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] This invention relates to a pneumatic extrusion system for use in direct-write 3D printing operations. It can completely isolate high-pressure gas from slurry 8 during the slurry 8 extrusion process, cleverly solving the problem of high-pressure gas easily mixing into slurry 8.

[0031] In terms of overall structure, such as Figure 1 As shown, the pneumatic extrusion system of this embodiment includes a barrel 5 with a cavity and a piston assembly slidably disposed in the cavity, and the two ends of the barrel 5 are respectively provided with an inlet and an outlet communicating with the cavity.

[0032] The piston assembly includes a first piston 2 and a second piston 1, and a connecting rod 3 connecting the first piston 2 and the second piston 1. The piston assembly divides the cavity into a material cavity 51 located between the first piston 2 and the discharge port, a connecting cavity 52 located between the first piston 2 and the second piston 1, and an air cavity 53 located between the second piston 1 and the feed port. The material cylinder 5 is provided with a connecting part for connecting the external environment and the connecting cavity 52.

[0033] Based on the overall introduction above, as an exemplary structure, it remains as follows: Figure 1 As shown, in this embodiment, the material cylinder 5 is provided with a material cylinder cover 7 located at the inlet, the air chamber 53 is formed between the second piston 1 and the material cylinder cover 7, and the material cylinder cover 7 is provided with an air inlet pipe 6 that is connected to both the air chamber 53 and the external air source.

[0034] Specifically, as a preferred embodiment, in this embodiment, the end of the material cylinder 5 away from the material cylinder cover 7 is provided with a printing nozzle 9, and the printing nozzle 9 is connected to the discharge port.

[0035] Here, we continue to combine Figure 1 As shown, the material cylinder 5 in this embodiment can be specifically configured to have a structure similar to a needle in general. The diameter of the inlet, which is also the diameter of the material cylinder 5, is much larger than the diameter of the printing nozzle 9 at the outlet, so as to facilitate the extrusion of the slurry 8.

[0036] To facilitate the disassembly and assembly of the pneumatic extrusion system and improve the ease of loading the slurry 8, in a preferred embodiment, the barrel cover 7 and the barrel 5 are screwed together. Additionally, in a preferred embodiment, a sealing ring is provided between the barrel cover 7 and the barrel 5 to ensure their airtightness.

[0037] In the specific screw connection structure between the barrel cover 7 and the barrel 5, an internal thread can be provided on the inner side wall of the barrel cover 7, and an external thread can be provided on the outer side wall of the barrel 5. The barrel 5 can be tightened with the barrel cover 7 by the cooperation of the external thread and the internal thread.

[0038] Of course, in this embodiment, in addition to being screwed together, the material cylinder cover 7 and the material cylinder 5 can also be configured with other detachable structures, such as snap-fit, or as before. Figure 1 As shown, the barrel cap 7 can preferably be a dispensing syringe adapter known to those skilled in the art to cooperate with the barrel 5. It is only necessary to ensure that the barrel cap 7 and the barrel 5 have good connection stability and are easy to disassemble and assemble.

[0039] Furthermore, in this embodiment, as an exemplary structure, the first piston 2, the second piston 1, and the connecting rod 3 are coaxially arranged. The advantage of this arrangement is that the structural design is reasonable, facilitating the assembly and disassembly of the piston assembly within the barrel 5, and also improving the stability of the slurry 8 extrusion.

[0040] In addition, as a preferred embodiment, in this embodiment, the connecting part includes a connecting vent 4 that penetrates the wall of the material cylinder 5. In specific implementation, the number, position and arrangement of the connecting vent 4 can be set and adjusted according to the actual exhaust and connection requirements. For example, it can be set in the middle of the length direction of the material cylinder 5, and there can be two, four or six vents arranged at intervals around the axial direction of the material cylinder 5.

[0041] It should be noted that, regardless of the number and arrangement of the connecting air holes 4, and the position of the piston assembly, the connecting air holes 4 should be positioned between the first piston 2 and the second piston 1 in the length direction of the barrel 5. The aforementioned connecting air holes 4 being located in the middle of the length direction of the barrel 5 is only a preferred embodiment.

[0042] In this embodiment, the pneumatic extrusion system can connect the external environment and the connecting cavity 52 through the connecting part when the first piston 2 is driven by pushing the second piston 1 to extrude the slurry 8 in the material chamber 51. This allows the slurry 8 to be continuously extruded only under the mechanical pushing action of the first piston 2. No gas enters the slurry 8 during the extrusion process, which effectively avoids the problems of solid-liquid separation and the generation of pores in the slurry 8. This separates the harmful effect of gas from the slurry 8, ensuring the quality stability and process reliability of the extruded slurry 8.

[0043] In addition, the present invention also relates to a method of using a pneumatic extrusion system, the method being applied to the aforementioned pneumatic extrusion system, and the method comprising the following steps:

[0044] When the second piston 1 is pushed by an external air source, the first piston 2, driven by the second piston 1, extrudes the slurry 8 in the material chamber 51. The slurry 8 is then connected to the external environment and the connecting chamber 52 through the connecting part, so that the slurry 8 is continuously extruded only under the mechanical pushing action of the first piston 2.

[0045] To elaborate, the specific steps for using this pneumatic extrusion system (including some assembly processes) are as follows:

[0046] First, the prepared slurry 8 is loaded into the barrel 5. Since the slurry 8 is viscous, it will stick to the inner wall of the barrel 5 during the loading process. In order to avoid the connecting air hole 4 and facilitate the subsequent pushing of the piston assembly, the slurry 8 is generally loaded near the printing nozzle 9 in the barrel 5, that is, at the discharge port.

[0047] Next, the piston assembly is pushed in. The piston assembly consists of a second piston 1 and a first piston 2 arranged vertically at intervals, connected by a connecting rod 3. Several connecting vents 4 are distributed near the center of the barrel 5. During the pushing of the piston assembly, the gas inside the barrel 5 is discharged through the connecting vents 4 and the printing nozzle 9, ensuring that no gas is mixed in with the slurry 8. The pushing is stopped when the slurry 8 is about to be extruded.

[0048] It should be noted that the connecting vent 4 should be positioned between the first piston 2 and the second piston 1 to ensure that the pressure between the first piston 2 and the second piston 1 is consistent with the external atmospheric pressure.

[0049] Finally, cover the barrel 5 with the barrel cover 7. The barrel cover 7 has a sealing ring inside. Tighten the barrel cover 7.

[0050] The working process of the pneumatic extrusion system in this embodiment is as follows: High-pressure gas is delivered into the barrel 5 through the air inlet pipe 6 and acts directly on the second piston 1. At this time, there is a controllable high-pressure environment between the barrel cover 7 and the second piston 1. The second piston 1 is subjected to pneumatic pressure and transmits the force to the first piston 2 through the connecting rod 3. Since the air pressure between the first piston 2 and the second piston 1 is the same as the atmospheric pressure of the external environment, the gas between the first piston 2 and the second piston 1 will not enter the slurry 8 through the contact position between the first piston 2 and the barrel 5, so that the first piston 2 simply squeezes the slurry 8 by mechanical force, forcing the slurry 8 to be extruded from the printing nozzle 9.

[0051] Understandably, this process effectively isolates the high-pressure gas from the slurry 8, cleverly solving the problem of high-pressure gas easily mixing into the slurry 8.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pneumatic extrusion system for use in direct-write 3D printing operations, characterized in that: It includes a material cylinder (5) with a cavity, and a piston assembly slidably disposed in the cavity, and the two ends of the material cylinder (5) are respectively provided with an inlet and an outlet communicating with the cavity; The piston assembly includes a first piston (2) and a second piston (1), and a connecting rod (3) connecting the first piston (2) and the second piston (1). The piston assembly divides the cavity into a material cavity (51) located between the first piston (2) and the discharge port, a communication cavity (52) located between the first piston (2) and the second piston (1), and an air cavity (53) located between the second piston (1) and the feed port. A communication portion for communicating with the external environment and the communication cavity (52) is provided on the material cylinder (5). The connecting part includes a connecting air hole (4) that passes through the cylinder wall of the material cylinder (5). The connecting vent (4) is located between the first piston (2) and the second piston (1) in the length direction of the barrel (5).

2. The pneumatic extrusion system according to claim 1, characterized in that: The material cylinder (5) is provided with a material cylinder cover (7) located at the inlet. The air chamber (53) is formed between the second piston (1) and the material cylinder cover (7). The material cylinder cover (7) is provided with an air inlet pipe (6) that is connected to both the air chamber (53) and an external air source.

3. The pneumatic extrusion system according to claim 2, characterized in that: The end of the material cylinder (5) away from the material cylinder cover (7) is provided with a printing nozzle (9), and the printing nozzle (9) is connected to the discharge port.

4. The pneumatic extrusion system according to claim 2, characterized in that: The barrel cover (7) is screwed to the barrel (5).

5. The pneumatic extrusion system according to claim 4, characterized in that: A sealing ring is provided between the material cylinder cover (7) and the material cylinder (5).

6. The pneumatic extrusion system according to claim 1, characterized in that: The first piston (2), the second piston (1), and the connecting rod (3) are arranged coaxially.

7. A method of using a pneumatic extrusion system, characterized in that, The method employs the pneumatic extrusion system described in any one of claims 1 to 6, and the method includes the following steps: The second piston (1) is pushed by an external air source so that when the first piston (2) is driven by the second piston (1) to extrude the slurry (8) in the material cavity (51), it can connect the external environment with the connecting cavity (52) through the connecting part, so that the slurry (8) is continuously extruded only by the mechanical pushing action of the first piston (2).

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