Patent Application
20160271869
The present invention relates to a device for printing three-dimensional structures, wherein droplets of printing material are deposited onto a substrate. Such devices comprise usually a printing head that ejects droplets, wherein the printing head scans the substrate several times in order to build up the three-dimensional structure layer by layer.
The success of such devices for printing three-dimensional structures, namely 3D-printer, motivates to upgrade those with respect to efficiency, flexibility, safety and costs. In this context it is also desirable to decrease the amount of energy needed for using a 3D-printer or increase the number of three-dimensional structures that can be produced using one 3D-printer, for example. Moreover a device for printing a three-dimensional structure should also fulfill safety requirements and protect objects and persons from damage that could be caused by at least one component of the 3D-printer, in particular the UV-light usually used for curing the deposited droplets. It is also desirable to improve the quality of the produced three-dimensional structure. In particular improvements could be related to the accuracy of depositing droplets onto the substrate during the printing process. Inaccuracies may raise from deviations in the absolute positional accuracy of the print head caused by movement changes that accumulate and lead to increasing errors in droplet positions in the end of the printing progress, for instance.
It is therefore an object of the present invention to improve the quality of the produced three-dimensional structure by providing a device for printing three-dimensional structures that deposits droplets of printing material more precisely than those known from the state of the art. Moreover it is desirable to realize a device for printing three-dimensional structures that can adapted easily to the requirements of the individual printing process.
The object is solved by a device for printing a three-dimensional structure by depositing droplets of printing material onto a substrate, wherein the device for printing a three-dimensional structure comprises a locally fixed framework and a mean for moving the substrate, wherein the locally fixed framework comprises a printing mean for depositing the droplets onto the substrate and the mean for moving the substrate is configured such that the substrate is movable relative to the locally fixed framework. For example the printing mean comprises a print head, i.e. nozzles for depositing droplets of printing material.
It is herewith advantageously possible to improve the accuracy of positioning the droplets onto the substrate compared to those known from the state of the art. Using the device for printing the three-dimensional structure according to the present invention enables determination of the position of the deposited droplets, i. e. the positioning of the deposited droplets, by changing the position of the substrate with respect to the printing mean mainly. As a result deviations of the print mean position caused by movement changes cannot accumulate and consequently the accuracy of positioning the deposited droplets is improved. It is also conceivable that the position of the substrate is monitored by a detection mean and subsequently the position of the substrate is corrected as soon as the current position of the substrate deviates from the position the substrate should have. In particular it is provided that the device is configured such that the three-dimensional structure is realized after a single pass of the substrate with respect to the printing mean. In such a scenario it is another advantage that a produced defect does not affect the subsequent printing process compared to a device that produces the three-dimensional structure layer by layer and therefore the shape of the layer depends on the shape of the previous layer, in particular on potential defect produced by forming the previous layer. In particular it is provided that the locally fixed framework is constructed as an arch, covering the region at which the printing process takes place. Thus the locally fixed framework protects the printing process from being affected by surroundings at least partially. It is also conceivable that the locally fixed framework is tube like shaped and the printing mean is arranged inside the tube surrounding the substrate. Preferably the mean for moving the substrate comprise a plate, wherein the substrate is arranged on top of the plate during the printing process. Provided that the three-dimensional structure is removed from the substrate after the printing process, the substrate may be permanently fixed to the mean for moving the substrate. In particular the plate comprises vacuum micropores and/or a ceramic plate. Moreover it is provided that the means for moving the substrate comprise guiding means that support accurate positioning of the substrate during the printing process. For instance stoppers, rollers and/or a rail system are arranged on the plate provided for positioning the substrate precisely.
According to a preferred embodiment of the present invention it is provided that the substrate has a main plane and the mean for moving the substrate is configured such that the substrate is movable
According to a preferred embodiment of the present invention it is provided that the printing mean is arranged to the locally fixed framework such that the distance between the substrate and the printing mean is variable. As a result the accuracy of positing the droplets is further improved whenever the distance between the substrate and the printing mean is reduced during the depositing process. Advantageously the deposited particles may be distributed over a smaller area or region compared to deposited particles distributed by a printing head being more distanced from the substrate.
According to a preferred embodiment of the present invention t it is provided that the means for moving the substrate and/or the printing head are configured such that the mean for moving the substrate and/or the printing head causes or determinates the positioning of the droplets deposited onto the substrate. In particular the mean for moving the substrate is configured to move the substrate to that position relative to the printing mean along the printing direction, which is provided for depositing the droplets of printing material. In particular it is provided that the printing mean moves slowly along the printing direction. It is also thinkable that the movement of the substrate may also be changed in speed in order to generate a layer of printing material having a variable height, provided the number of droplets per time ejected by the printing mean stays constant mainly. It is also thinkable that the movement of the substrate and the movement of the printing means are synchronized in order to realize a desired distribution of droplets on the layer. Thus the device for printing the three-dimensional structure configured according to the present embodiment facilities a plurality of different and individually adapted methods for depositing droplets onto the substrate.
According to a preferred embodiment of the present invention it is provided that the locally fixed framework comprises a tank including printing material, wherein the tank is configured such that the tank supplies the printing mean with printing material and wherein the tank is connected reversibly or interchangeably to the locally fixed framework. Integrating the tank into the locally fixed framework has the advantage of guaranteeing a permanent supply of printing material to the printing mean without moving the tank during the printing process. Consequently it is possible to reduce the amount of energy needed for using the device for printing the three-dimensional structure. Avoiding the movement of the tank during the printing process may particularly advantageous whenever a three-dimensional structure is intended to be generated that needs a big amount of printing material being deposited without interruption of the printing process (maybe caused by refilling or reloading printing material). It is also an advantage that the tank is connected to the locally fixed framework reversibly or interchangeably, since the tank, in particular in dependency of its content or its size, may be replaced by another tank in order to adapt the tank to the printing process. Preferably the tank has a capacity up to 6 liters. It is also thinkable that the fixed framework comprises a plurality of tanks including different printing material respectively. Furthermore it is conceivable that the fixed framework also comprises a premix chamber, wherein the premix chamber is configured such that a first printing material out of a first tank is mixed with a second printing material out of a second tank. It is also thinkable that the second tank includes a material for mixing with the first printing material, wherein the material for mixing with the first printing material changes the properties of the first printing material advantageously. For example the material for mixing dilutes the first printing material. Preferably the printing material in the premix chamber is used for realizing the three-dimensional structure. Moreover the tank or the plurality of tanks is configured such that the printing material is changeable during the printing process. In particular the fixed framework and/or the printing means are designed such that the printing mean is cleaned, in particular the printing mean is cleaned on the flight during the printing process. Moreover it is thinkable that the second tank or a cleaning device mounted to the fixed framework includes a cleaning solution that cleans the printing mean. Moreover it is thinkable that the printing mean comprises a print head and is configured such that the printing material is released from the printing mean permanently in order to avoid a blocking of the nozzles for instance. In particular the substrate comprises a waste tank that collects a part of the printing material that is not intended for creating the three-dimensional structure. Moreover the waste tank is able to recirculate printing material back to the tank or the printing mean for releasing printing material from the printing mean permanently. It is also thinkable that the printing head, which is included in the printing mean, is configured such that the printing material is recirculated inside the print head in order to avoid drying of the printing material inside the printing head. It is also thinkable that the printing material includes particles made from metal. Furthermore the printing mean, in particular the printing head, comprises pumping and/or filtering devices for manipulating the printing material.
According to another embodiment of the present invention it is provided that the tank and/or the printing means are configured such that the droplets of printing material are released from the printing mean with a constant pressure. Consequently the deposition of the droplets of the printing material is substantially reproducible. In particular the tank or the printing mean comprises a device for observing and controlling the pressure. It is also thinkable that a flow of the printing material in the printing mean, in particular in its printing head, is controlled.
According to a preferred embodiment of the present invention it is provided that the framework comprises a light source for curing the deposited droplets of printing material, wherein the light source is connected reversibly or interchangeably to the locally fixed framework. Preferably the light source is provided for curing the deposited droplets and is arranged such that a light cone of the light source is directed to the substrate, in particular to the droplets on the substrate. In particular it is provided that the light sources are arranged such that no light encounters the printing head in order to avoid curing droplets that provided for ejection. Such an arrangement may reduce the probability of blocking a nozzle that is intended for ejecting the droplets of printing material. Due to a reversible connection between the locally fixed framework and the light source the light source is interchangeable and may advantageously adapted to the printing process individually.
According to a preferred embodiment of the present invention it is provided that the mean for moving the substrate is attached to the locally fixed framework. By combining the locally fixed framework and the mean for moving the substrate the probability is reduced that the locally fixed framework and the mean for moving the substrate are shifted to each other. In particular the stability for positioning the substrate relative to the printing head is improved. It is also thinkable that the mean for moving the substrate is connected to the locally fixed framework reversibly or interchangeably. Moreover it is conceivable the mean for moving the substrate is configured such that the substrate rotates about an axis perpendicular to the transport direction. Preferably an angle of rotation of the substrate is between 0° and 90°. In particular the substrate passes the fixed framework several times and after each pass the substrate rotates around a specific angle, for example 90°.
According to another embodiment of the present invention it is provided that the substrate is heated or cooled in order to improve the curing process of the printing material.
According to a preferred embodiment of the present invention it is provided that the device for printing a three-dimensional structure comprises an encapsulation, wherein the encapsulation surrounds at least a part of the locally fixed framework, the means for moving the substrate and/or the substrate, wherein the encapsulation is configured such that light is blocked by the encapsulation. Such an encapsulation may protect the substrate, the printing process the three-dimensional structure, the mean for moving the substrate and/or the device of printing the three-dimensional structure from being affected by surroundings that could interfere with the components of the device for printing the three-dimensional structure. As a result a preferably environment for printing a three-dimensional structure of high quality is provided. Moreover the encapsulation blocks light, in particular UV- or IR-light, and therefore the encapsulation can prevent humans and/or objects from being damaged by UV- or IR-light emitted, reflected and/or scattered from the device for printing the three-dimensional structure advantageously. For this purpose the encapsulation may be coated by a coating, in particular a UV or IR-grade coating, that guarantees blocking the light intended for curing the deposited droplets. It is also conceivable that the encapsulation is coated such that the light is reflected from the wall of the encapsulation to the droplets of printing material on the substrate. The reflected light supports the printing process and the amount of energy for producing the three-dimensional structure is reduced positively. It is also thinkable that printing material is cured by an electron beam and the encapsulation protects the surrounding from the electron beam.
According to a preferred embodiment of the present invention it is provided that the encapsulation forms a cleanroom including the substrate, the locally fixed framework and the means for moving the substrate. Such a cleanroom has the advantage that the printing process is isolated from the surrounding that may affect the printing process negatively. It is also thinkable that the cleanroom is filled with a gas, such as nitrogen or oxygen, that may affect the printing process positively. In particular the dosage of the gas is adjusted such that the curing is accelerated or decelerated. Moreover it is thinkable that the dosage and/or the type of the gas is changed during the printing process. It is also conceivable that the pressure within the cleanroom is adapted to the printing process. In particular it is herewith advantageously possible to adapt easily the parameters of the environment such as temperature, humidity or air pressure to those desired for the printing process individually.
According to a preferred embodiment of the present invention it is provided that the cleanroom comprises a cleaning device that is configured such that the substrate is cleaned before the droplets of printing material are deposited onto the substrate.
According to a preferred embodiment of the present invention it is provided that the printing mean comprises
According to another embodiment of the present invention it is provided that the device for printing a three-dimensional structure comprises a coating device that coats the substrate and/or the three-dimensional structure. In particular it is conceivable that the coating device pre-coats the substrate before the droplets of the printing material are deposited onto the substrate.
Another subject of the present invention is a method for printing a three-dimensional structure using a device as it is described above, wherein the substrate is moved relative to the locally fixed framework.
It is herewith advantageously possible providing a printing method, wherein the movement of the printing mean is restricted and therefor the positioning of the deposited droplets becomes more accurate compared to those known in the state of the art.
According to a preferred embodiment of the present invention it is provided that the three-dimensional structure is printed in a single pass. The single pass corresponds to one pass or scan of the substrate with respect to the substrate. Using such a method for printing has the advantage that the deposition of the droplets does not depend on defects that were made in a previous step of the printing process. For instance it is conceivable that a layer is generated with a vacancy erroneously. The deposited droplets of the next layer may fill the vacancy before the droplets are cured. Consequently the vacancy may keep up and the size of the defect may even grow till the last layer is deposited for forming the three-dimensional structure. As a result the defects may be on the surface of the final three-dimensional structure and reduce therefore the quality of the produces three-dimensional structure disadvantageously. This potential source of error may be circumvented by producing three-dimensional structure in a single pass according to the present invention, advantageously.
According to a preferred embodiment of the present invention it is provided that the droplets of printing material are deposited onto the substrate in a first step and the droplets of the printing material are cured in a second step, wherein the printing head is moved along the printing direction during the first step and wherein the printing head is removed along the direction opposed to the printing direction. In that manner the printing process is accelerated and the efficiency improved since the droplets are deposited and cured by the printing head moving forward and backward only once.
According to a preferred embodiment of the present invention it is provided that in a third step the printing process is observed by the sensor mean, in a forth step the printing process is configured in dependency of the observation made in the third step and in a fifth step the three-dimensional structure is coated. According to this embodiment the printing process the three-dimensional structure is monitored and corrected in a positive manner, whenever the printing process leads to a defect that may impair the quality of the final three-dimensional structure. In particular the coating process according to the fifth step enables manipulating the surface of the three-dimensional structure with respect to its color or other properties.
Another subject of the present invention is a printed article, printed with a method descripted above. The printing article takes advantage of the positive effects of the methods descripted above.
These and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. The description is given for the sake of example only, without limiting the scope of the invention. The reference figures quoted below refer to the attached drawings.
The present invention will be descripted with respect to particular embodiments and with the reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some elements may be exaggerated and not drawn on scale for illustrative purposes.
Where an indefinite or definite article is used when referring to a singular noun, e. G. “a”,“an”, “the”, this includes a plurals of the noun unless something else is specifically stated.
Furthermore, the terms first, second, third and the like in the description and in the claims are used to distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described of illustrated herein.
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| Number | Date | Country | Kind |
|---|---|---|---|
| 13189085.7 | Oct 2013 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/071830 | 10/13/2014 | WO | 00 |
