3D printer with printing head

Abstract

The invention relates to a 3D printer (150) having a print head (100) which comprises: an actuator device (110) arranged in a housing (1) of the print head (100) for actuating a piston (3) of the print head (100); a nozzle head (6) having one or more heating elements (61, 63) for converting the printable material (10) from a solid phase (10) via a plastic phase (11) into a liquid phase (12); and a nozzle (8) for discharging a liquid phase (12) of the material (10) from the nozzle head (6), the nozzle (8) being at least partially closable by a closure device (90) during a compression process of the material (10, 11, 12). The invention is characterized in that the closing device (90) has an elastically yielding closing means (91) for closing the nozzle (8), in particular a nozzle opening (180).

Description

Field of the Invention

[0001] The present invention relates to a 3D printer having a print head. Background Art

[0002] A 3D printer for a material that can vary in its viscosity obtains the solid phase of the material as the starting material, thereby generating a liquid phase and selectively applying the liquid phase to parts belonging to the object to be produced. Such a 3D printer includes a print head in which the starting material is prepared for printing. In addition, a device is provided for generating a relative movement between the print head and the work surface on which the object is to be formed. Here, only the print head can be moved, or only the work surface can be moved, or both the print head and the work surface can be moved simultaneously.

[0003] The print head has a first operating state and a second operating state. In the first operating state, the liquid material is discharged from the print head, and in the second operating state, no liquid material is discharged from the print head. For example, when moving to another position on the work surface and no material should be discharged on the way, the second operating state is occupied. For example, the switching between the two operating states of the print head can be achieved by turning on or off the feed of the solid starting material.

[0004] The most widely used is "Fused Deposition Modeling" (FDM), in which the filament made of the starting material is melted in an electrically heatable extrusion nozzle and applied layer by layer to a platform. The starting material in the form of such a filament is very expensive.

[0005] From WO 22195031 A1, a print head for a 3D printer is known, in which the particles are plasticized by a piston and a heating section. When the piston presses on the particles, the particles are compressed, and the nozzle of the print head is closed at this time. The nozzle can be closed, for example, by a closing valve or by positioning the print head on a plate in the structural space of the printer. In addition, it has also been proposed that the print head can be moved to the printed area of the component to close the nozzle.

[0006] The disadvantages of these solutions are that the closing valve on the print head will increase the structural space requirement around the nozzle, which may cause a collision between the print head and the component. In addition, the weight of the print head increases, thereby limiting the dynamics during printing. Positioning the print head on the structural plate will, on the one hand, cause wear of the nozzle, which reduces the printing quality, and on the other hand, in order to close the nozzle, the print head must be horizontally moved to the structural plate or the structural plate is moved to the print head. Summary of the Invention

[0007] The object underlying the present invention is to provide a 3D printer having a print head that closes the nozzle without wear during the compression of the melt, so that the print head can provide a high-quality melt with repeatable quality.

[0008] A 3D printer with a print head has been developed within the scope of the present invention.

[0009] The present invention relates to a 3D printer with a print head, comprising actuator means for actuating a piston arranged in the housing of the print head, a nozzle head having one or more heating elements for transforming a printable material from a solid phase via a plastic phase into a liquid phase, and a nozzle for outputting the liquid phase of the material from the nozzle head, wherein the nozzle can be at least partially closed by a closing device during the compression of the material.

[0010] According to the invention, the closing device has an elastically yielding closing element for closing the nozzle, in particular the nozzle opening.

[0011] The elastically yielding closing element of the closing device of the 3D printer yields when closing the nozzle, in particular the nozzle opening, and thereby advantageously causes wear-free closing to build up pressure or compress the liquid phase of the printable material. Thereby, a better closing of the nozzle, in particular the nozzle opening, is achieved, and thereby the target pressure in the system can be advantageously reached faster. In addition, the service life of the nozzle is increased by wear-free closing and the desired printing quality can be ensured over a longer period of time. Furthermore, by means of the present invention, it is not necessary to horizontally manipulate the closing device or the print head in order to close the nozzle, and thereby materials for horizontal positioning and the corresponding manufacturing costs can be saved.

[0012] The actuator means for actuating the piston can be an electric motor, which for example has a mechanical transmission, or a hydraulic actuator having a hydraulic pressure source. Compared with a hydraulic actuator, the electric motor as an actuator means has a lower weight, which thereby advantageously causes high dynamics of the entire printer and the printing process, since only a small mass has to be accelerated. The hydraulic actuator advantageously enables high forces when actuating the piston.

[0013] The 3D print head according to the invention is particularly suitable for a method comprising the following process, which is part of the process steps from filling to opening the nozzle of the print head during print preparation. This print preparation process is also called a refilling process, since it is a repetitive process that can be arbitrarily repeated during the printing of a component. The refilling process is a method for providing a printable melt for the operation of the print head of a 3D printer. The refilling process is advantageous because it causes homogenization of the melt.

[0014] The compression of the material during the compression process includes, for example, the following steps:

[0015] - pre-compressing the material by the feed of the piston,

[0016] - Closing the nozzles of the print head by a closing device with an elastically yielding closing element,

[0017] - Feeding and compressing the material by a piston, and

[0018] - Holding the piston in a holding position.

[0019] During the compression process, the pre-compression of the material is carried out in a pressure- and / or force-controlled manner by feeding of the piston, wherein the pre-compression is carried out up to a position which is reached when reaching and / or exceeding the material-related slope and / or the material-related slope angle of the force and / or pressure curve.

[0020] The pre-compression is carried out by actuating the piston in a force- or pressure-controlled manner by an actuator device, wherein the target position of the bottom of the piston is located in the first third starting from the cooling zone of the plasticizing zone. The granules are compressed in the plasticizing zone by feeding of the piston, wherein at the same time there is a melt in the melt zone between the cavity and the nozzle. The plasticized granules are thus pressed into the melt in the mixing zone.

[0021] By lowering the piston in the direction of the nozzle, the melt has been discharged from the nozzle, thereby expelling any air or air inclusions that may still be present from the nozzle head. Thereby the nozzle is cleared.

[0022] After reaching the target position of the pre-compression, the nozzles of the print head are closed by the closing device with an elastically yielding closing element.

[0023] In a first embodiment of the invention, the closing element comprises a pressure element, wherein the pressure element is made of an elastic material. In one embodiment, this is an elastic ball. In another embodiment, the elastic pressure element comprises a surface with a negative form having a nozzle, in particular in the form of a nozzle opening.

[0024] The elastic material of the corresponding pressure element yields when the print head is moved onto the closing device, conforms to the nozzle, in particular the nozzle opening, and closes it. Thereby, wear on the nozzle is advantageously reduced.

[0025] In a preferred embodiment, the closing element comprises a pressure element and a spring. In one embodiment, the pressure element of this embodiment is a ball. In another embodiment, the pressure element comprises a surface with a negative form having a nozzle, in particular in the form of a nozzle opening.

[0026] In an extended embodiment, the spring of the closing element has a spring force which is greater than the maximum pressure occurring during the compression of the material.

[0027] When the print head moves onto the closing device, in particular horizontally onto the pressure device, the spring yields. Here, the pressure device closes the nozzle, in particular the nozzle opening. Thereby, wear on the nozzle is advantageously reduced.

[0028] In an extended embodiment, the closing device is arranged outside the printing area of the print head. Thereby, the closing of the nozzle is carried out outside the printing area, so that no additional attachments for closing the nozzle need to be provided on the print head. The resulting possible slender structure of the print head advantageously avoids collisions of the print head with components, and the print head is not limited in its dynamics due to additional weight.

[0029] The 3D print head according to the invention can carry out the refilling or repacking process more quickly and thereby cause a smaller temperature difference on the component itself during the manufacture of the component. In addition, a better melt quality and thereby a better component quality are achieved.

[0030] In the next method step, with the nozzle closed, the compression of the material is carried out in a pressure-controlled manner by the feed of the piston, and it is moved into the holding position until the so-called peak pressure is reached.

[0031] The piston is held in the holding position, wherein during the holding process the pressure and temperature of the liquid phase are measured, and the measured values are checked by an analysis and evaluation unit to control the function of the compression process.

[0032] In addition, while the piston is held in the holding position, the nozzle is also closed by means of a closing device with an elastically yielding closing element.

[0033] For the compression of the material, the piston is fed in a pressure-controlled manner by an actuator device until a defined peak pressure and thus the so-called peak pressure position are reached. Here, the nozzle is still closed by means of a closing device with an elastically yielding closing element.

[0034] Subsequently, the peak pressure position is held for a predefined period related to the material, so that the peak pressure position is also the holding position of the print head.

[0035] While the piston is held in the holding position, the nozzle is closed by means of a closing device with an elastically yielding closing element.

[0036] By the holding process, residual air is expelled and the melt is homogenized in the mixing zone. Thereby, a better energy flow is achieved and a more uniform material is produced.

[0037] The holding process described here is also used for analysis and system checks of the print head, since the following effects can occur during pressure measurement. An increase in the pressure of the pressure in the melt will mean that the melt releases gas, because for example the temperature of the melt is too high. An excessive melt temperature is undesirable because an air plasma can be generated, which will lead to chemical decomposition. A strong pressure drop in the melt pressure can for example mean that the system of the print head is not sealed or that there is still too much air in the system. This effect can occur for example when there is too much cold material in the cavity, because the temperature management of the print head has not been optimally adjusted.

[0038] Furthermore, the pressure preparation of the liquid phase can include the following steps:

[0039] - Actively decompressing the liquid phase by pulling back the piston according to the previously determined spring constant, and

[0040] - Opening the nozzle by moving the print head away from the closing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Further measures for improving the present invention will be shown in detail below together with the description of the preferred embodiments of the present invention according to the drawings.

[0042] The drawings show:

[0043] Figure 1 : A 3D printer according to the present invention with a print head;

[0044] Figure 2 : A first embodiment of a nozzle closed by a closing device, and

[0045] Figure 3 : A second embodiment of a nozzle closed by a closing device. DETAILED DESCRIPTION

[0046] Figure 1 A 3D printer 150 having a print head 100 is shown, including an actuator device 110 for controlling a piston 3 disposed in a housing 1 of the print head 100, a nozzle head 6 having one or more heating elements 61, 63 for converting a printable material 10 from a solid phase 10 via a plastic phase 11 into a liquid phase 12, and a nozzle 8 for outputting the liquid phase 12 of the material 10 from the nozzle head 6, wherein the nozzle 8 can be at least partially closed by a closing device 90 during the compression process of the materials 10, 11, 12 (for this also see Figure 2 ). Figure 1 The open state of the nozzle 8 is shown, Figure 2Shows the closed state of the nozzle 8. According to the invention, the 3D printer has a closing device 90 which has an elastically yielding closing element 91 for closing the nozzle 8, in particular the nozzle opening 180.

[0047] The closing device 90 with the closing element 91 is arranged on a device 151 outside the printing area of the print head 100. The device 151 is fixedly arranged in the construction space or construction chamber of the 3D printer 150. Furthermore, a coordinate system 152 with x, y and z axes is shown. The print head 100 can move in the x and y directions, and a construction plate or substrate carrier (on which the component to be printed is printed), not shown, can move in the z direction.

[0048] The print head 100 shown here includes, for example, a region 4 for guiding the piston 3 in the print head 100.

[0049] Figure 1 Shows the piston 3 in its initial position for filling the print head 100 with printable material 10, which is supplied to the print head 100 by a supply device 2.

[0050] The supply device 2 is funnel-shaped, and the material 10, preferably in the form of granules, is filled into the opening of the supply device 2 from above.

[0051] During the filling process of the print head 100, the nozzle 8 is closed, especially when compressed, as shown in Figure 2 and Figure 3 and when the piston 3 is actuated by the actuator device 110, the materials 10, 11, 12 arranged in the cavity 40 and the melting chamber 81 are compressed by piston feed.

[0052] The heating elements 61, 63 in the nozzle head 6 heat the materials 10, 11, 12 in the cavity 40 and the melting chamber 81 until the liquid phase 12 of the material reaches its process temperature and can be output from the nozzle 8.

[0053] During the printing process and the output of the liquid phase 12 or melt of the material, the print head 100 moves in the x and y directions and constructs the component, not shown, layer by layer. When the melt is exhausted or when the printing process requires it, the piston 3 is pulled back and granules are filled into the cavity 40. For the refilling process, the print head 100 is positioned on the closing device 90.

[0054] Figure 2 and Figure 3 Shows an embodiment in which the nozzle 8 is closed, where the nozzle is positioned on or above the closing device 90. To close the nozzle 8, during the refilling process, the print head 100 or the extruder is moved outside the construction plate or substrate carrier and positioned on or above the closing device 90.

[0055] Figure 2 Shows a first embodiment of a closing device 90 arranged on a device 151 of a 3D printer 150, wherein the closing device 91 includes a pressure device 92, and the pressure device 92 is made of an elastic material.

[0056] In this embodiment, the pressure device 91 is shown as spherical and has elastically conformed to the nozzle 8 or the nozzle opening 180, thereby closing it.

[0057] As an alternative embodiment, the pressure device 92 may include a surface having a negative shape of the nozzle 8, in particular the nozzle opening 180, in order to close the nozzle, in particular the nozzle opening.

[0058] Figure 3 Shows a second embodiment of a closing device 90 arranged on a device 151 of a 3D printer 150, wherein the closing device 91 includes a pressure device 92 and a spring 93. The spring 93 is arranged in a housing 94 of the closing device 90. The spherical pressure device 92 is placed above the spring 93 and closes the nozzle 8 or the nozzle opening 180. As an alternative embodiment, the pressure device 92 may have a surface including a negative shape of the nozzle 8, in particular the nozzle opening 180, in order to close the nozzle, in particular the nozzle opening.

[0059] The spring 93 of the closing device 91 has a spring force greater than the maximum pressure that occurs during the compression of the materials 10, 11, 12.

[0060] To close the nozzle 8, the print head 100 having the nozzle 8 is moved above the elastic pressure device 92. Here, the nozzle 8 presses the pressure device 92 or the ball into the housing 94 of the closing device 90 through the spring 93, thereby orienting the pressure device 92 as concentrically as possible with respect to the nozzle and closing the nozzle.

[0061] The spring force or the closing force is greater than or equal to the target pressure or the peak pressure of the system during refilling.

Claims

1. A 3D printer (150) having a print head (100), said print head comprising: An actuator device (110) arranged in a housing (1) of the print head (100) for manipulating a piston (3) of the print head (100), A nozzle head (6) having one or more heating elements (61, 63) for transforming a printable material (10) from a solid phase (10) via a plastic phase (11) into a liquid phase (12), and A nozzle (8) for outputting the liquid phase (12) of the material (10) from the nozzle head (6), wherein the nozzle (8) can be at least partially closed by a closing device (90) during the compression process of the material (10, 11, 12), Characterized in that The closing device (90) has an elastically yielding closing element (91) for closing the nozzle (8), in particular the nozzle opening (180).

2. The 3D printer (150) according to claim 1, characterized in that The closing element (91) comprises a pressure element (92), wherein the pressure element (92) is made of an elastic material.

3. The 3D printer (150) according to claim 1, characterized in that The closing element (91) comprises a pressure element (92) and a spring (93).

4. The 3D printer (150) according to claim 3, characterized in that The spring (93) of the closing element (91) has a spring force greater than the maximum pressure occurring during the compression process of the material (10, 11, 12).

5. The 3D printer (150) according to any one of claims 2 or 3, characterized in that The pressure element (92) is a ball.

6. The 3D printer (150) according to any one of claims 2 or 3, characterized in that The pressure element (92) has a surface with a negative shape of the nozzle (8), in particular the nozzle opening (180).

7. The 3D printer (150) according to any one of the preceding claims, characterized in that The closing device (90) is arranged outside the printing area of the print head (100).

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