Multi-axis 3D printing system with curable resin mass filling and a 3D printing method with curable resin mass filling

Abstract

The application relates to a multi-axis 3D printing system with curable resin mass filling, comprising a robotic arm with a hybrid printhead comprising an FFF printhead, a biaxial positioner with a working platform, and a resin filling system, wherein the hybrid head (1a) comprises a resin delivery head (14) in fluid flow communication with the resin print filling system, and an ultraviolet light source (10), wherein the resin delivery head comprises a pneumatic valve (6) for the control of resin delivery. The invention also relates to the method of printing using the aforementioned system.

Description

[0001] Multi-axis 3D printing system with curable resin mass filling and a 3D printing method with curable resin mass filling

[0002] The invention relates to a seven-axis 3D printing system with robotic arms and biaxial positioners used to achieve fast and precise printing. This system integrates the fused filament fabrication technology with the resulting voids being filled with curable resin to obtain a hybrid print. The main objective of the system is to strengthen the printed elements, especially along the Z axis, and to increase the printing speed.

[0003] In the paper titled "Hybrid Additive Manufacturing" (Konvicny, Jiri and Rossing, Lars, Technical Disclosure Commons, (January 06, 2021)), a combination of Fused filament fabrication (FFF) and stereolithography (SLA) 3D printing techniques is presented as a means to ensure better isotropicity of FFF-printed parts.

[0004] Patent application no. US2023191651A1 presents a 6-axis 3D printing system. The presented system comprises a robotic arm with a 3D printhead and a rotary table. Similarly, a robotic tool with a rotary working table is presented in patent application no. US2022184880A1.

[0005] Patent application no. US2017369731A1 presents a method of printing using gel materials, where shear forces change during the flow of gel through the deposition nozzle resulting in rapid collapse of material elasticity. Elasticity is restored immediately after leaving the nozzle, and the gel solidifies to maintain its shape and strength.

[0006] International PCT application no. W02024079018A1 discloses a multi-axis 3D printing system comprising a robotic arm and a rotary work table capable of changing the work plane inclination angle.

[0007] Another patent application no. US2015314534A1 describes a device and method that support the production of large hollow 3D objects or thin-walled coatings, including curved surfaces with high and low curvature change rates, while alleviating or significantly reducing the need for supporting structures.

[0008] The invention relates to a multi-axis 3D printing system with curable resin mass filling. The technical problem posed by the invention is to provide a 3D printing system capable of printing without the need for supports, reducing the printing time, and ensuring reinforcement of the print over the entire cross-section rather than only from the outside. In addition, the system should deliver high quality prints. An additional technical problem consists in the reduced strength of the printed elements in the direction transverse to the applied layer as compared to longitudinal strength (lower strength along the Z axis). Unexpectedly, the above problems are solved by the present invention.

[0009] The invention relates to a multi-axis 3D printing system with curable resin mass filling, comprising a robotic arm with a hybrid printhead comprising an FFF printhead, a biaxial positioner with a working platform, and a resin filling system, characterized in that the hybrid head comprises a resin delivery head in fluid flow communication with the resin print filling system, and an ultraviolet light source, wherein the resin delivery head comprises a pneumatic valve for the control of resin delivery. Preferably, the resin delivery head is oriented at an angle with respect to the printhead.

[0010] In a preferred embodiment of the invention, the resin filling system comprises a resin reservoir in fluid flow communication through a membrane pump with a resin delivery head, and a compressor.

[0011] In the next preferred embodiment of the invention, the multi-axis 3D printing system is a seven-axis system.

[0012] In a further preferred embodiment of the invention, the hybrid head comprises a thermoplastic material presence sensor.

[0013] In another preferred embodiment of the invention, the ultraviolet light source is integrated with the resin delivery head.

[0014] The invention also relates to the method of 3D printing with curable resin mass filling, comprising the steps of: a) providing a multi-axis 3D printing system with curable resin mass filling as defined in the first object of the invention; b) creating a print scaffold on the printing substrate; c) creating the side walls of the 3D print, wherein following the creation of a print layer using the FFF head , the internal print voids are filled with UV-curable resin from the resin delivery head and the layer is cured using an ultraviolet light source, the steps being repeated alternately until the print is completed. In a preferred embodiment of the invention, the resin is cured during or after the delivery of a resin layer, preferably a full resin layer.

[0015] The solution according to the invention has a number of advantages. Using resin as a 100% filler for the inside voids of the print reduces the time required to complete the print and increases its strength along the Z axis. In addition, reinforcement of the print occurs over the entire cross-section rather than only from the outside. Thanks to the membrane pump, constant pressure of the resin feed, and thus a precisely defined volume of the resin output over time, can be obtained. The valve located at the resin outlet nozzle allows to immediately cut off the outflow of the resin after the print area is completely filled, eliminating the effect of the resin leaking from the nozzle after the resin feed is completed, translating onto the high quality of the created object.

[0016] The embodiments of the invention are shown in the drawings, wherein:

[0017] Figure 1 shows a 3D printing system of the invention;

[0018] Figure 2 shows an exemplary cross-section of the print structure, wherein the outer walls consist of layers of sequentially deposited filaments of a thermoplastic material. The filling of the inner void is achieved using extruded resin delivered in filaments with a thickness and width greater than the filament of the thermoplastic material; and Figure 3 presents the hybrid printhead.

[0019] Example 1. A multi-axis 3D printing system with curable resin mass filling.

[0020] The multi-axis 3D printing system according to the invention comprises a robotic arm (1) provided with a hybrid printhead (la), a biaxial positioner (2) with a working platform (3), a resin print filling system, and an FFF system (Fig. 1). As used herein, multiaxiality refers to the ability of the tip of the robotic arm to move in seven degrees of freedom relative to the working platform. This will be presented later in the description. The robotic arm (1) facilitates precise positioning and manipulation of the hybrid printhead (la) in seven axes so as to enable the creation of complex geometries. The biaxial positioner (2) is responsible for the maintenance of stable position of the working platform (3) with respect to the hybrid printhead (la) during the printing process. The hybrid printhead (la) of the printer shown in Figure 3 comprises two material delivery assemblies: an FFF head (8) for the delivery of thermoplastic material (9), preferably provided with a thermoplastic material presence sensor (13), and a resin delivery head (14) with a pneumatically controlled resin outlet valve (6) comprising a resin inlet (15) from a membrane pump (5) and a pneumatic hose inlet (16) to control the valve position (6). The resin delivery head (14) comprises the final working part of the resin filling system. The FFF head (8) for the delivery of the thermoplastic material (9) comprises the final working part of the FFF printing system. Unlike the prior art, the FFF head (8) and the resin delivery head (14) are not coaxial, i.e. the thermoplastic material (9) is not delivered from the FFF head (8) in parallel to the axis of resin outflow from the delivery head (14). The axes of the FFF head (8) and the resin delivery head are oriented at an angle, preferably at an angle of about 90°, to each other. This is particularly evident in Figure 3. The advantages of such a system include, firstly, the possibility of using a hybrid head (la) featuring two heads (8, 14), each of said two heads having the freedom of being tilted in relation to the working platform without being exposed to collision with the other head. The second advantage is that the resin delivery head (14) can be rotated while printing using the FFF head (8), so that the effect of gravitational leakage of the resin after pouring is limited.

[0021] The thermoplastic material (9) feeding system is not shown in the figures. However, it is known in the art and can be easily applied by a person skilled therein.

[0022] The resin filling system further comprises an air pressure generating compressor (7) operatively connected, i.e. by means liquid resin supply lines, to a resin reservoir (4) operatively connected to a membrane pump (5) operatively connected to a resin delivery head (14) complete with a valve (6) for precise control of the resin delivery. The resin delivery head (14) functions in cooperation with an ultraviolet radiation source (10). The source (10) is integrated with the resin delivery head (14) as shown in Figure 3. Thanks to this design, the resin delivered from the head (14) can be cured immediately. This prevents the resin from being spilled or dripping uncontrollably. In addition, it gives the possibility of precise and controlled filling of the voids within the print produced using the FFF head (8) from thermoplastic material (9), resulting in the reinforcement of the print structure and precise curing after resin pouring.

[0023] Using the FFF head(8), functionally mounted on the hybrid head (la) of the robotic arm (1), the print scaffold (12) is created. The 3D printing method consists in the production of the base and the side walls of the print scaffold (12) using the FFF head (8) to deliver thermoplastic material (9). This is shown schematically in Figure 2. Using the robotic arm (1) with five degrees of freedom, functionally connected to the biaxial positioner (2) with two degrees of freedom, the head can be positioned with seven degrees of freedom relative to the printed object. After the creation of the side walls, the liquid filling (11) is fed by changing the robot tool to the resin delivery head (14), with the controlled robot (1) using said resin delivery head (14) to deliver the liquid material (resin) by extruding it under pressure from the tank (4). The resin may be any one- or multi-component UV-curable resin used in the art. Curing is carried out in a continuous manner during the delivery by means of light being emitted from the UV radiation source (10) located near the delivery head (14), or after the delivery of the full layer, by including a separate process with the UV radiation source (10) passing above the layer by the movements of the robotic arm (1). The robot tool is then changed back to the FFF printhead (8) and the process cycle is repeated until the full height of the product is reached.

Claims

Claims1. A multi-axis 3D printing system with curable resin mass filling, comprising a robotic arm with a hybrid printhead comprising an FFF printhead, a biaxial positioner with a working platform, and a resin filling system, characterized in that the hybrid head (la) comprises a resin delivery head (14) in fluid flow communication with the resin print filling system, and an ultraviolet light source (10), wherein the resin delivery head comprises a pneumatic valve (6) for the control of resin delivery.

2. The system according to claim 1 characterized in that the resin filling system comprises a resin reservoir (4) in fluid flow communication through a membrane pump (5) with a resin delivery head (14), and a compressor (7).

3. The system according to claim 1 characterized in that the multi-axis 3D printing system is a seven-axis system.

4. The system according to claim 1 characterized in that the hybrid head comprises a thermoplastic material presence sensor (13).

5. The system according to claim 1 characterized in that the ultraviolet light source (10) is integrated with the resin delivery head (14).

6. The system according to claim 1 characterized in that the resin delivery head (14) is oriented at an angle with respect to the printhead (8).

7. A method of 3D printing with curable resin mass filling, comprising the steps of: d) providing a multi-axis 3D printing system with curable resin mass filling according to claim 1 e) creating a print scaffold on the printing substrate; f) creating the side walls of the 3D print, characterized in that following the creation of a print layer using the FFF head (8), the internal print voids are filled with UV-curable resin from the resin delivery head (14) and the layer is cured using an ultraviolet light source (10), the steps being repeated alternately until the print is completed.

8. The method according to claim 7 characterized in that the resin is cured during or after the delivery of a resin layer, preferably a full resin layer.

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