3D printing head, printer provided with the printing head and printing method

Abstract

A 3D printing head, a printer provided with the printing head and a printing method, wherein one end of a containing cavity of the printing head is provided with a discharge head, a screw is arranged in the containing cavity, a driving device drives the screw to rotate, a feeding device is in communication with the containing cavity and supplies material to the containing cavity, a heating device is arranged on the containing cavity or the screw, so that the material in the containing cavity is heated, a supercritical fluid conveying device is in communication with the containing cavity and inputs supercritical fluid into the containing cavity, and the containing space in the containing cavity increases from the communication position of the supercritical fluid conveying device and the containing cavity to the discharge head. The mixing amount of the supercritical fluid into the material is improved, and the efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of 3D printing additive manufacturing technology, and more particularly to a 3D print head, a printer equipped with the print head, and a printing method. Background Technology

[0002] 3D printers are a type of rapid prototyping technology. They are a technology that uses digital model files as a basis and bondable materials such as powdered metal or plastic to build objects layer by layer.

[0003] For example, Fused Deposition Modeling (FDM) is one of the mainstream technologies in additive manufacturing. It utilizes the heat-melting and adhesive properties of thermoplastic materials (ABS or PLA), heating the material into a molten state within an extrusion mechanism. Under programmed control, the extrusion mechanism moves along the contour of the model in the XY plane and the Z-axis. The extruded material solidifies and bonds with the surrounding material. Each layer is built up layer by layer until the model is complete.

[0004] The main technical shortcomings of existing industrial-grade fused deposition modeling (FDM) printing equipment are:

[0005] First, the existing PLA material has a high density, around 1.3 kg / m3; the material is a solid structure, making the printed products heavy. Second, the existing technology material is a solid structure, so the printed products do not dissipate heat completely, resulting in greater internal stress and warping and deformation. Third, due to the solid material, the amount of printing material consumed is large, resulting in higher printing costs.

[0006] Furthermore, when using a conventional printhead to connect to a supercritical fluid, the amount of supercritical fluid mixed into the material is limited, which means that the number of micropores formed is small, and the material is prone to stagnation at the mixing point, resulting in poor mixing effect. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a 3D printing head, a printer equipped with the printing head, and a printing method. One technical problem solved by this invention is that it addresses the issue of solidity in fused deposition modeling (FDM) printed products while increasing the amount of supercritical fluid incorporated into the material, thereby improving efficiency.

[0008] One technical solution adopted by the present invention to solve its technical problem is:

[0009] A 3D printing head includes a receiving cavity, a screw, a supercritical fluid conveying device, a driving device, a feeding device, a heating device, and a discharging head. The discharging head is provided at one end of the receiving cavity, and the screw is provided inside the receiving cavity. The driving device drives the screw to rotate. The feeding device is connected to the receiving cavity and supplies material to the receiving cavity. The heating device is provided on the receiving cavity or the screw to heat the material in the receiving cavity. The supercritical fluid conveying device is connected to the receiving cavity and inputs supercritical fluid into the receiving cavity. The receiving space in the receiving cavity increases from the connection between the supercritical fluid conveying device and the receiving cavity towards the discharging head.

[0010] Preferably, at least one of the receiving cavity and the screw has a gradually changing diameter, that is, the receiving space in the receiving cavity gradually increases from the connection between the supercritical fluid conveying device and the receiving cavity towards the discharge head.

[0011] Preferably, the increase in the accommodating space in the accommodating cavity from the connection between the supercritical fluid conveying device and the accommodating cavity towards the discharge head is positively correlated with the amount of supercritical fluid to be mixed into the material per unit volume.

[0012] Preferably, the screw has a spiral groove on its outer periphery, and the depth of the spiral groove gradually decreases from the feeding device end to the discharge head end.

[0013] Preferably, the discharge head includes a mixing section, a contraction section, and a protruding section. The mixing section is connected to the receiving cavity. A contraction section with a gradually decreasing diameter is provided downstream of the mixing section. A protruding section extending outward is provided at the end of the contraction section. The mixing section includes at least one of a forward impeller and a reverse impeller. At least one of the forward impeller and the reverse impeller is provided in the mixing section. The material moving towards the discharge port drives the forward impeller to rotate clockwise and drives the reverse impeller to rotate counterclockwise.

[0014] Preferably, the forward impeller and the reverse impeller are arranged adjacent to each other; the forward impeller includes forward blades that are twisted 180° to 270°; the reverse impeller includes reverse blades that are twisted 180° to 270°; the protruding section of the discharge head is made of copper and extends outward by 1 to 5 mm.

[0015] Preferably, the heating device is located between the feeding device and the receiving cavity and the discharge head; the feeding device supplies PLA particles to the receiving cavity; the outer periphery of the screw is coated with polytetrafluoroethylene.

[0016] Preferably, the supercritical fluid delivery device includes a supercritical fluid generator and a controllable injector. The fluid generator is connected to the receiving cavity through the controllable injector. The supercritical fluid delivery device is an isobaric supercritical fluid device, and the output is supercritical carbon dioxide fluid.

[0017] A 3D printer that uses the aforementioned 3D print head.

[0018] A method for operating a 3D printer, using the aforementioned 3D printer for additive printing.

[0019] Preferably, based on the density value of the extruded material at the outlet, the gradual contraction of the screw corresponding to the connection between the supercritical fluid conveying device and the receiving cavity in the direction of the discharge head is changed, thereby adjusting the space used to accommodate the supercritical fluid and material mixture.

[0020] Preferably, when material needs to be extruded, the drive motor drives the screw to rotate forward to extrude the material; when material extrusion is not required, the drive motor drives the screw to rotate in reverse to retain the material in the receiving cavity.

[0021] As can be seen from the above technical solution, one beneficial effect of this invention is that it improves upon the shortcomings of industrial-grade fused deposition modeling (FDM) printing equipment by introducing supercritical fluid into the printing material. This reduces the density of the printed product from a high density of 20-50% compared to the original solid material, resulting in a much lighter printed product and lower printing costs by 16-20%. Furthermore, the heat distribution in the printed product is more uniform and rapid, reducing internal stress and effectively suppressing warping and deformation, thus improving the quality of the printed product. Simultaneously, increasing the amount of supercritical fluid mixed into the material enhances the micropore formation rate, making printing smoother and more convenient, and improving printing efficiency. Attached Figure Description

[0022] Appendix Figure 1 This is a schematic diagram of the structure of a 3D printing head according to one embodiment of the present invention.

[0023] Appendix Figure 2 This is a schematic diagram of the structure of a 3D printing head according to another embodiment of the present invention.

[0024] Appendix Figure 3 This is a cross-sectional view of the mixing section of the 3D printing head output head according to one aspect of the present invention.

[0025] In the figure: 10 receiving cavity, 20 screw, 21 spiral groove, 30 supercritical fluid conveying device, 31 supercritical fluid generating device, 32 controllable injector, 40 drive device, 50 feeding device, 60 heating device, 70 discharge head, 71 mixing section, 710 forward impeller, 711 reverse impeller, 72 contraction section, 73 protrusion section. Detailed Implementation

[0026] The technical solution of one embodiment of the invention will be further described in detail with reference to the accompanying drawings.

[0027] Example 1:

[0028] A 3D printing head includes a receiving cavity 10, a screw 20, a supercritical fluid conveying device 30, a driving device 40, a feeding device 50, a heating device 60, and a discharge head 70. The discharge head 70 is provided at one end of the receiving cavity 10. The screw 20 is provided inside the receiving cavity 10. The driving device 40 drives the screw 20 to rotate. The feeding device 50 is connected to the receiving cavity 10 and supplies material to the receiving cavity 10. The heating device 60 is provided on the receiving cavity 10 or the screw 20 so that the material in the receiving cavity 10 is heated. The supercritical fluid conveying device 30 is connected to the receiving cavity 10 and inputs supercritical fluid into the receiving cavity 10. The receiving space in the receiving cavity 10 increases from the connection between the supercritical fluid conveying device 30 and the receiving cavity 10 towards the discharge head 70.

[0029] The containment space in the containment cavity 10 increases from the connection between the supercritical fluid conveying device 30 and the containment cavity 10 towards the discharge head 70. The specific increase can be a step-by-step increase, that is, the space of this containment cavity 10 increases in a stepped manner; it can also be a gradual increase, that is, the space increases in an arc or cone shape; or it can be an irregular increase, that is, the increase rate of each segment of this containment space is different; or it can even be that a sudden decrease blocking section is inserted in the middle of the increase of this containment space to improve the mixing efficiency.

[0030] Supercritical fluid is introduced into the 3D print head to obtain a printing material containing micropores. However, if the condition of the receiving cavity 10 is not changed, directly introducing supercritical fluid will result in two problems: one is that the introduced supercritical fluid will suddenly slow down the flow rate of the previously printed material, causing the material flow to be uneven and resulting in blockage; the other is that the mixing efficiency of the introduced supercritical fluid is not high, because the proportion of supercritical fluid mixed in is very limited due to space constraints. Therefore, this application gradually increases the receiving space after the supercritical fluid inflow point. On the one hand, this increases the space occupied by the inflowing supercritical fluid in the receiving cavity 10, so that the material flow rate is not significantly affected, thus ensuring smooth printing without blockage; on the other hand, the gradual increase in space is conducive to supercritical fluid foaming, which greatly improves the mixing efficiency of supercritical fluid.

[0031] Example 2:

[0032] See attached document Figure 1 As shown,

[0033] A 3D printing head includes a receiving cavity 10, a screw 20, a supercritical fluid conveying device 30, a driving device 40, a feeding device 50, a heating device 60, and a discharge head 70. The discharge head 70 is provided at one end of the receiving cavity 10. The screw 20 is provided inside the receiving cavity 10. The driving device 40 drives the screw 20 to rotate. The feeding device 50 is connected to the receiving cavity 10 and supplies material to the receiving cavity 10. The feeding device 50 is a PVC transparent steel wire tube. The heating device 60 is provided on the receiving cavity 10 or the screw 20 to heat the material in the receiving cavity 10. The supercritical fluid conveying device 30 is connected to the receiving cavity 10 and inputs supercritical fluid into the receiving cavity 10. The receiving space in the receiving cavity 10 gradually increases from the connection between the supercritical fluid conveying device 30 and the receiving cavity 10 towards the discharge head 70. Furthermore, the increase in the containment space of the containment cavity 10 from the connection between the supercritical fluid conveying device 30 and the containment cavity 10 towards the discharge head 70 is positively correlated with the amount of supercritical fluid to be mixed into the material per unit volume.

[0034] Based on the material density required for the product, the injection volume of supercritical fluid and the increase from the supercritical fluid conveying device 30 to the discharge head 70 at the connection between the receiving cavity 10 and the discharge head 30 are determined. The screw 20 is replaced as needed, thereby enabling the efficient printing of products with different densities.

[0035] Example 3:

[0036] See attached document Figure 2 As shown,

[0037] A 3D printing head includes a receiving cavity 10, a screw 20, a supercritical fluid conveying device 30, a driving device 40, a feeding device 50, a heating device 60, and a discharge head 70. The discharge head 70 is provided at one end of the receiving cavity 10. The screw 20 is provided inside the receiving cavity 10. The driving device 40 drives the screw 20 to rotate. The feeding device 50 is connected to the receiving cavity 10 and supplies material to the receiving cavity 10. The feeding device 50 is a PVC transparent steel wire tube. The heating device 60 is provided on the receiving cavity 10 or the screw 20 to heat the material in the receiving cavity 10. The supercritical fluid conveying device 30 is connected to the receiving cavity 10 and inputs supercritical fluid into the receiving cavity 10. The receiving space in the receiving cavity 10 gradually increases from the connection between the supercritical fluid conveying device 30 and the receiving cavity 10 towards the discharge head 70. Furthermore, the increase in the containment space of the containment cavity 10 from the connection between the supercritical fluid conveying device 30 and the containment cavity 10 towards the discharge head 70 is positively correlated with the amount of supercritical fluid to be mixed into the material per unit volume.

[0038] The screw 20 has a spiral groove 21 on its outer periphery, and the depth of the spiral groove 21 gradually decreases from the feeding device 50 end to the discharge head 70 end.

[0039] This heating device 60 is installed on the receiving cavity 10 or the screw 20, and the spiral groove 21 is gradually tapered. This design results in a smaller space between the screw 20 and the receiving cavity 10 in the initial material heating section, while the spiral groove 21 is deeper, ensuring that both the screw 20 and the receiving cavity 10 are heated. This design increases both the material receiving space and the heating surface area, maximizing the effective heating of the material. As the spiral groove 21 gradually becomes shallower, it increases the extrusion pressure of the molten material, ensuring its basic quantity. This gradual design accelerates the heating rate of a unit of material and ensures sufficient extrusion pressure in the later stages, preventing voids and improving printing efficiency and quality.

[0040] Example 4:

[0041] A 3D printing head includes a receiving cavity 10, a screw 20, a supercritical fluid delivery device 30, a drive device 40, a feeding device 50, a heating device 60, and a discharge head 70.

[0042] A discharge head 70 is provided at one end of the receiving cavity 10. A screw 20 is provided inside the receiving cavity 10. A drive device 40 drives the screw 20 to rotate. A feeding device 50 is connected to the receiving cavity 10 and supplies material to the receiving cavity 10. The feeding device 50 is a PVC transparent steel wire tube. A heating device 60 is provided on the receiving cavity 10 or the screw 20 so that the material in the receiving cavity 10 is heated. A supercritical fluid conveying device 30 is connected to the receiving cavity 10 and inputs supercritical fluid into the receiving cavity 10.

[0043] The containment space in the containment cavity 10 gradually increases from the connection point between the supercritical fluid conveying device 30 and the containment cavity 10 towards the discharge head 70. Furthermore, the increase in the containment space in the containment cavity 10 from the connection point between the supercritical fluid conveying device 30 and the containment cavity 10 towards the discharge head 70 is positively correlated with the amount of supercritical fluid to be mixed into the material per unit volume.

[0044] The screw 20 has a spiral groove 21 on its outer periphery, and the depth of the spiral groove 21 gradually decreases from the feeding device 50 end to the discharge head 70 end.

[0045] The discharge head 70 includes a mixing section 71, a shrinking section 72, and a protruding section 73. The mixing section 71 is connected to the receiving cavity 10. Downstream of the mixing section 71, there is a shrinking section 72 with a gradually decreasing diameter. At the end of the shrinking section 72, there is an outwardly extending protruding section 73. The protruding section 73 of the discharge head 70 is made of copper and extends outward by 1 to 5 millimeters.

[0046] The mixing section 71 includes at least one of a forward impeller 710 and a reverse impeller 711, both disposed within the mixing section 71. The forward impeller blades are twisted by 180° to 270°. The reverse impeller 711 includes reverse blades twisted by 180° to 270°. Material moving towards the discharge port drives the forward impeller 710 to rotate clockwise and the reverse impeller 711 to rotate counterclockwise. (See attached diagram.) Figure 3 As shown, the forward impeller 710 and the reverse impeller 711 are arranged adjacent to each other to achieve more uniform mixing.

[0047] This type of printhead with a mixing section 71, especially when the forward impeller 710 and the reverse impeller 711 are arranged adjacently, significantly improves the material mixing efficiency compared to a printhead with only a forward impeller 710 or only a reverse impeller 711.

[0048] Example 5:

[0049] A 3D printing head includes a receiving cavity 10, a screw 20, a supercritical fluid delivery device 30, a drive device 40, a feeding device 50, a heating device 60, and a discharge head 70.

[0050] A discharge head 70 is provided at one end of the receiving cavity 10. A screw 20 is provided inside the receiving cavity 10. The driving device 40 drives the screw 20 to rotate. The feeding device 50 is connected to the receiving cavity 10 and supplies PLA granules to the receiving cavity 10. The feeding device 50 is a PVC transparent steel wire tube. The heating device 60 is provided on the receiving cavity 10 or the screw 20 so that the material in the receiving cavity 10 is heated. The heating device 60 provided on the receiving cavity 10 is located between the feeding device 50 and the receiving cavity 10 and the discharge head 70. The heating device 60 provided on the screw 20 makes the screw 20 heat up as a whole.

[0051] The containment space in the containment cavity 10 gradually increases from the connection point between the supercritical fluid conveying device 30 and the containment cavity 10 towards the discharge head 70. Furthermore, the increase in the containment space in the containment cavity 10 from the connection point between the supercritical fluid conveying device 30 and the containment cavity 10 towards the discharge head 70 is positively correlated with the amount of supercritical fluid to be mixed into the material per unit volume.

[0052] The supercritical fluid delivery device 30 is connected to the receiving cavity 10. The supercritical fluid delivery device 30 includes a supercritical fluid generator 31 and a controllable injector 32. The fluid generator is connected to the receiving cavity 10 through the controllable injector 32, which precisely supplies supercritical fluid to the receiving cavity 10. The supercritical fluid delivery device 30 is an isobaric supercritical fluid device, and its output is supercritical carbon dioxide fluid.

[0053] Example 6:

[0054] A 3D printer is a printer that uses any one of the 3D print heads in Examples 1 to 5.

[0055] Example 7:

[0056] A method of operating a 3D printer is a method of additive printing using the printer described in Example 6.

[0057] Example 8:

[0058] A method of operating a 3D printer is a method of printing using the printer described in Example 6.

[0059] Based on the density value of the extruded material at the outlet, the gradual contraction of the screw 20 corresponding to the connection between the supercritical fluid conveying device 30 and the receiving cavity 10 in the direction of the discharge head 70 is changed, thereby adjusting the space used to accommodate the supercritical fluid and material mixture.

[0060] When material needs to be extruded, the drive motor drives the screw 20 to rotate forward and extrude the material; when material extrusion is not required, the drive motor drives the screw 20 to rotate in reverse and retain the material in the receiving cavity 10.

Claims

1. A 3D printing head, comprising a receiving cavity, a screw, a supercritical fluid conveying device, a driving device, a feeding device, a heating device, and a discharging head, wherein a discharging head is provided at one end of the receiving cavity, a screw is provided inside the receiving cavity, the driving device drives the screw to rotate, the feeding device is connected to the receiving cavity and supplies material to the receiving cavity, the heating device is provided on the receiving cavity or the screw to heat the material in the receiving cavity, and the supercritical fluid conveying device is connected to the receiving cavity and inputs supercritical fluid into the receiving cavity, characterized in that: The containment space in the containment cavity increases from the connection between the supercritical fluid conveying device and the containment cavity towards the discharge head; The discharge head includes a mixing section, a shrinking section, and a protruding section. The mixing section is connected to the receiving cavity. A shrinking section with a gradually decreasing diameter is provided downstream of the mixing section. A protruding section extending outward is provided at the end of the shrinking section. The mixing section includes at least one of a forward impeller and a reverse impeller. At least one of the forward impeller and the reverse impeller is provided in the mixing section. The material moving towards the discharge port drives the forward impeller to rotate clockwise and drives the reverse impeller to rotate counterclockwise. The forward impeller and the reverse impeller are arranged adjacent to each other; At least one of the receiving cavity and the screw has a gradually changing diameter, that is, the receiving space in the receiving cavity gradually increases from the connection between the supercritical fluid conveying device and the receiving cavity towards the discharge head; The increase in the containment space of the containment cavity from the connection between the supercritical fluid conveying device and the containment cavity towards the discharge head is positively correlated with the amount of supercritical fluid to be mixed into the material per unit volume.

2. The 3D printing head according to claim 1, characterized in that: The screw has a spiral groove on its outer periphery, and the depth of the spiral groove gradually decreases from the feeding device end to the discharge head end.

3. The 3D printing head according to claim 2, characterized in that: The forward impeller and the reverse impeller are arranged adjacent to each other; the forward impeller includes forward blades, which are twisted 180° to 270°; the reverse impeller includes reverse blades, which are twisted 180° to 270°; the protruding section of the discharge head is made of copper and extends outward by 1 to 5 mm.

4. The 3D printing head according to claim 1, characterized in that: The heating device is located between the feed device and the receiving cavity and the discharge head; the feed device supplies PLA particles to the receiving cavity; the outer periphery of the screw is coated with polytetrafluoroethylene.

5. The 3D printing head according to claim 1, characterized in that: The supercritical fluid delivery device includes a supercritical fluid generator and a controllable injector. The fluid generator is connected to the receiving cavity through the controllable injector. The supercritical fluid delivery device is an isobaric supercritical fluid device, and the output is supercritical carbon dioxide fluid.

6. A 3D printer, characterized in that: Use any one of the 3D printing heads described in claims 1 to 5.

7. A method for operating a 3D printer, characterized in that: Additive printing is performed using the 3D printer described in claim 6.

8. The method of operating a 3D printer according to claim 7, characterized in that: Based on the density value of the extruded material at the discharge port, the gradual contraction of the screw corresponding to the connection between the supercritical fluid conveying device and the receiving cavity in the direction of the discharge head is changed, thereby adjusting the space used to accommodate the supercritical fluid and material mixture.

9. The method of operating a 3D printer according to claim 7, characterized in that: When material needs to be extruded, the drive motor drives the screw to rotate forward and extrude the material; when material extrusion is not required, the drive motor drives the screw to rotate in reverse and retain the material in the receiving cavity.

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