Printing device for a 3d printer

Abstract

The invention relates to a printing device (10) for a 3D printer. The printing device comprises a metering unit (18) for melting and plasticizing a material (38) to be printed and a delivery unit (14) for printing the material (38) provided via the metering unit (18). The metering unit (18) and the delivery unit (14) are arranged separately from each other and can be connected to each other, wherein the delivery unit (14) can be transported to the metering unit (18) in order to receive material (38) and, in order to connect the delivery unit (14) to the metering unit (18), a nozzle (74) of the delivery unit (14) and a coupling point (62) of the metering unit (18) come into contact with each other.

Description

[0001] Description

[0002] Title:

[0003] Printing device for a 3D printer

[0004] The present invention relates to a printing device for a 3D printer and a method for operating such a printing device.

[0005] State of the art

[0006] A 3D printer for a material with variable viscosity receives a solid phase of this material as its starting material, converts it into a liquid phase, and selectively applies this liquid phase to the areas belonging to the object being produced. Such a 3D printer includes a print head in which the starting material is prepared for printing. The material is conveyed through channels within the print head.

[0007] Furthermore, means are provided to generate relative movement between the printhead and the work surface on which the object is to be created. Either only the printhead, only the work surface, or both the printhead and the work surface can be moved. To influence the dispensing of material onto the work surface, an actuator is usually provided in the printhead, which applies a force to a metering zone.

[0008] A printhead for a 3D printer is known from WO 2018 / 086792 Al.

[0009] The printhead has a feeder through which a raw material to be printed is fed to the printhead. Inside the printhead, this raw material is melted and plasticized. This molten material is then conveyed within the printhead to an outlet opening, through which it is applied to a printing area. Disclosure of the invention

[0010] Within the scope of the invention, a printing device for a 3D printer was developed. This printing device comprises a dosing unit for melting and plasticizing a material to be printed and a discharge unit for printing the material supplied via the dosing unit.

[0011] In the context of the invention, a dosing unit is understood to be, in particular, an area to which a raw material is fed, wherein this raw material is melted and plasticized in the dosing unit. Furthermore, the melted material can also be dispensed in a metered manner. The discharge unit is an area from which the material can be dispensed for the production of a 3D object.

[0012] According to the invention, the metering unit and the discharge unit are arranged separately from each other and can be connected to each other, wherein the discharge unit can be transported to the metering unit for receiving material and a nozzle of the discharge unit and a coupling point of the metering unit are connected to each other for connecting the discharge unit with the metering unit.

[0013] In the invention, the metering unit and the discharge unit are thus separated from each other. However, both units can be connected to receive material. Accordingly, the discharge unit has a volume in which a certain quantity of the molten material can be received.

[0014] It was recognized that this approach offers advantages over printheads where the dosing and dispensing units are integrated into a single printhead. In particular, separating the two units results in a lighter weight being moved, primarily consisting of the dispensing unit and the molten material. Consequently, the dynamics of such a 3D printer are improved. Separating the different functions allows for a more optimized design of each unit. For example, an actuator that exerts force on the material in the dosing unit no longer affects the dispensing volume. This allows the actuators, for instance, to be designed more cost-effectively and efficiently to achieve the desired result.

[0015] Separating the metering unit from the discharge unit offers the additional advantage of improved material utilization. With a printhead that combines metering and discharge units, the injected material must be used up to prevent the molten material from solidifying later in the discharge unit. This often results in incomplete material use and waste. In contrast, the metering unit can dispense only the required amount of material into the discharge unit. This maximizes material utilization and reduces costs, enabling more economical production with such a printing system.

[0016] To further increase efficiency, a preferred embodiment of the invention provides several discharge units that alternately interact with a single metering unit to receive material. This means that only one metering unit is required for multiple discharge units. Thus, a separate metering unit is not needed for each discharge unit. This increases the utilization of the metering unit, thereby improving the efficiency of such a system.

[0017] In a further preferred embodiment of the invention, for example in an industrial plant, the discharge units are assigned to different, separate pressure chamber units. Thus, the discharge units of several printing processes, each producing a different workpiece, can operate with only one metering unit. A separate transport system is preferably provided for transporting the discharge unit to the metering unit. This transport system is a system that moves the discharge unit from the area where a workpiece is printed to the metering unit. This can be achieved, for example, via a rail system along which the discharge unit is transported. In one embodiment, a printing axis can be extended to reach the metering unit.

[0018] This is particularly advantageous for smaller systems.

[0019] In another embodiment, the discharge unit can also be transported to the dosing unit by a robot. Similarly, the discharge unit can be transported back from the dosing unit to the workpiece. Such a transport system is particularly advantageous for larger systems.

[0020] The transport system offers the advantage that the discharge units can be kept simple and specifically tailored to their discharge function. This reduces the cost of the discharge units. Ideally, the transport system carries multiple discharge units, thus improving its utilization. Consequently, the costs for such a transport system can be further reduced.

[0021] In an advantageous further development, the transport system includes a heated transport carrier in which the discharge unit is housed. The transport carrier is an integral part of the transport system, directly supporting the discharge unit. The discharge unit is at least partially enclosed on the outside by the heated portion of the transport carrier. Heating the transport carrier minimizes the cooling of the molten material within the discharge unit during transport. Consequently, the storage time of the material in the discharge unit is extended.

[0022] The discharge unit is advantageously arranged in the printing unit in a way that allows for easy exchange. In other words, the discharge unit currently in use can be replaced with a different one. This has the advantage that a discharge unit with a different nozzle opening, cross-section, or volume can be used for printing. The color of the discharge unit can also be changed. This allows the discharge unit to be optimally adapted to the required workpiece manufacturing process, thus improving workpiece production. Changing the discharge unit is advantageously possible during operation. This eliminates the need for production interruptions, making production faster and more economical. The discharge unit is preferably changed automatically, thereby reducing personnel costs.

[0023] Preferably, the discharge unit has a discharge piston that interacts with a means by which a force can be applied against the filling direction of the discharge unit when material is being received. Thus, during the filling of the discharge unit at the metering unit, a force is exerted against the material being received. The discharge piston is a piston that is movable within the discharge unit and acts on the material received in the discharge unit. In a preferred embodiment, the means is a spring. The force has the advantage that the means dampens the return movement of the discharge piston. This ensures an air-free filling of the discharge unit.

[0024] In a practical design, a discharge piston is provided, which is driven by a servo motor, so that the material can be conveyed out for printing. A servo motor has the advantage of increasing the accuracy and reproducibility of the material discharge from the discharge unit. This significantly improves the quality of the workpiece.

[0025] Unlike a printhead known from the prior art, the servomotor of the discharge unit only acts on a homogeneous melt. This means that low power is required for such a servomotor, making its implementation feasible due to reduced costs.

[0026] To ensure the high forces required in the metering unit, it preferably features a metering piston for dispensing the material, driven by a hydraulic system or an electric motor. The metering piston is also movably arranged within the metering unit and exerts a force on the material to convey it from the metering unit to the discharge unit. Unlike the discharge unit, where high accuracy is required, the metering unit can thus be supplied with sufficient force. By separating the discharge unit from the metering unit, each unit can be optimized for its specific function.

[0027] The invention further specifies a method for operating such a printing device. This method comprises the steps of transporting the discharge unit to the metering unit, connecting the discharge unit to the metering unit, filling the discharge unit with material to be printed, and transporting the discharge unit to the area to be printed. When the metering unit is connected to the discharge unit, both units are sealed together so that the material can be transferred from the metering unit to the discharge unit. The aforementioned advantages can be achieved with such a method.

[0028] Exemplary embodiments of the invention are shown in the drawing and explained in more detail in the following description. It shows:

[0029] Figure 1 Exemplary embodiment of a pressure device during the filling of a discharge unit,

[0030] Figure 2 Exemplary embodiment of a pressure device during transport of the discharge unit, Figure 3 Exemplary embodiment of a pressure device with several discharge units which are arranged in different pressure chamber units, and

[0031] Figure 4 Method for operating the pressure device.

[0032] Figure 1 shows an embodiment of a pressure device 10 during the filling of a discharge unit 14. Figure 1 is shown in a sectional view. In addition to the discharge unit 14, the pressure device 10 has a metering unit 18. The metering unit 18 consists of a base body 22 to which a filling hopper 26 is attached. A raw material 30, which is in solid form, can be poured into the filling hopper 26. The filling hopper 26 is directly connected to a metering chamber 34 formed by the base body 22. In this metering chamber 34, the raw material 30 is melted and plasticized to form a pressureable material 38.

[0033] The metering chamber 34 has a lateral metering piston opening 42. A metering piston 46 is arranged in this metering piston opening 42 and projects into the metering chamber 34. A metering piston force FD can be applied to the material 38 in the metering chamber 34 via the metering piston 46, so that it can be pressed towards a metering feed opening 50 opposite the metering piston opening 42.

[0034] At the metering feed opening 50, the metering unit 18 has a coupling element 54 which forms a channel 58, so that the material 38 dispensed via the metering feed opening 50 can be conveyed to a coupling point 62 of the coupling element 54. The discharge unit 14 is arranged at the coupling point 62, so that this discharge unit 14 can receive the molten material 38.

[0035] The discharge unit 14 has a discharge body 66, which forms a discharge chamber 70 in which molten material 38 can be received. A nozzle 74 is formed at one end of the discharge body 66, which is connected to the coupling point 62, through which the molten material 38 can be received. The material 38 is also applied to a workpiece (not shown) through this nozzle 74.

[0036] Within the discharge chamber 70, a discharge piston 78 is arranged, through which the material 38 can be discharged. Above the discharge piston 78, a means 82 is arranged, through which a force F is applied during filling. F is applied against a filling direction. In this embodiment, the means 82 is designed as a schematically indicated spring. The force F exerted on the discharge piston 78 FThis ensures that the discharge unit 14 is filled without air. During filling, the discharge piston 78 is moved towards the spring 82.

[0037] Figure 2 shows an embodiment of the pressure device 10 during transport of the discharge unit 14. In particular, this figure shows a transport system 86 of the pressure device 10. In this embodiment, the transport system 86 is formed from an axle unit 90, which is schematically indicated here as being connected to a motor M. The discharge unit 14 can be transported between the metering unit 18 and a workpiece to be manufactured (not shown) via this transport system 86. The transport can be carried out automatically.

[0038] In this embodiment, the transport system 86 additionally includes a transport carrier 94, which surrounds the discharge unit 14 on the outside. The transport carrier 94 specifically includes a heater 98, which heats the material in the discharge unit 14 during transport. This allows the storage time of the material in the discharge unit 14 to be extended, thus enabling, for example, longer transport distances or transport times. In an embodiment not shown here, the transport system 86 can also be implemented using a robot.

[0039] Figure 3 shows an embodiment of the printing device 10 with several discharge units 14, which are arranged in different pressure chamber units 102. Each pressure chamber unit 102 produces a different workpiece. A discharge unit 14 is arranged in each pressure chamber unit 102, and each discharge unit 14 is received by a printhead body 106, over which the discharge unit 14 is movable. The printhead body 106, like the transport carrier 94, can also be equipped with a heater (not shown).

[0040] The pressure chamber units 102 are connected to a dosing unit 18 via a single transport system 86. Accordingly, several discharge units 14 can be connected to a single dosing unit 18 via a single transport system 86. This improves the utilization of the components.

[0041] Figure 4 shows a method for operating the printing device 10. In a first step A, the discharge unit 14 is transported to the metering unit 18. In a second step B, the discharge unit 14 is coupled to the metering unit 18, forming a sealing connection between them. In a subsequent step C, the metering unit 18 fills the discharge unit 14. The discharge unit 14 can be completely filled, or it can be filled with only a specific quantity of material. This quantity is measured to ensure complete material utilization. In a final step D, the filled discharge unit 14 is transported to a printing area. This process can be repeated multiple times during printing.

Claims

Claims 1. Printing device (10) for a 3D printer comprising a metering unit (18) for melting and plasticizing a material (38) to be printed and a discharge unit (14) for printing the material (38) supplied via the metering unit (18), characterized in that the metering unit (18) and the discharge unit (14) are arranged separately from each other and can be connected to each other, wherein the discharge unit (14) can be transported to the metering unit (18) for receiving material (38) and a nozzle (74) of the discharge unit (14) and a coupling point (62) of the metering unit (18) are connected to each other for connecting the discharge unit (14) with the metering unit (18).

2. Pressure device (10) according to claim 1, characterized in that several discharge units (14) are provided which alternately cooperate with a single metering unit (18) to receive material (38).

3. Pressure device (10) according to claim 2, characterized in that the discharge units (14) are assigned to different, separate pressure chamber units (102).

4. Pressure device (10) according to one of the preceding claims, characterized in that a separate transport system (86) is provided for transporting the discharge unit (14) to the metering unit (18).

5. Printing device (10) according to claim 4, characterized in that the transport system (86) has a heated transport carrier (94) in which the discharge unit (14) is received.

6. Pressure device (10) according to one of the preceding claims, characterized in that the discharge unit (14) is arranged interchangeably in the pressure device (10).

7. Pressure device (10) according to one of the preceding claims, characterized in that the discharge unit (14) has a discharge piston (78) which cooperates with a means (82) with which a force (FF) can be applied against a filling direction of the discharge unit (14) when receiving material (38).

8. Printing device (10) according to one of the preceding claims, characterized in that the discharge unit (14) has a discharge piston (78) which is driven by a servo motor, so that the material (38) can be conveyed for printing.

9. Pressure device (10) according to one of the preceding claims, characterized in that the metering unit (18) has a metering piston (46) for dispensing the material (38) in the metering unit (18), which is driven by a hydraulic system or an electric motor.

10. Method for operating a pressure device (10) according to any one of the preceding claims, wherein the method comprises the steps: Transporting (A) the discharge unit (14) to the metering unit (18), connecting (B) the discharge unit (14) to the metering unit (18), filling (C) the discharge unit (14) with material (38) to be printed, and Transport (D) the discharge unit (14) to an area to be printed.

Images