POST-EXPOSURE UNIT

Abstract

A post-exposure unit for post-exposure of a body manufactured using an additive manufacturing method from a substance curable by radiation, the post-exposure unit comprising at least one radiation source configured for post-exposure, the post-exposure unit including at least one radiation sensor, the radiation sensor being adapted to capture radiation emitted by the radiation source. The post-exposure unit has a receiving space for receiving a body to be post-exposed. The radiation sensor is adapted to capture radiation emitted by the radiation source and traverses at least a part of the receiving space at least once.

Claims

1. A post-exposure unit for post-exposure of a body manufactured using an additive manufacturing method from a substance curable by radiation, the post-exposure unit comprising: at least one radiation source configured for post-exposure; wherein the post-exposure unit has at least one radiation sensor, wherein the radiation sensor is configured for capturing radiation emitted by the radiation source, wherein the post-exposure unit has a receiving space for receiving a body to be post-exposed, wherein the radiation sensor is configured to capture radiation emitted by the radiation source and traverses at least a part of the receiving space at least once.

2. The post-exposure unit according to claim 1, wherein the radiation sensor is configured to capture the radiation intensity and/or the radiation wavelength of the radiation emitted by the radiation source.

3. The post-exposure unit according to claim 1, wherein the radiation sensor and the radiation source are arranged on opposite sides of the receiving space.

4. The post-exposure unit according to claim 3, wherein the post-exposure unit comprises at least two radiation sensors and at least two radiation sources, wherein both a radiation source and a radiation sensor are arranged on at least one side of the receiving space.

5. The post-exposure unit according to claim 3, wherein the receiving space is formed in a receiving basin, wherein the at least one radiation source and/or the at least one radiation sensor is arranged outside the receiving basin.

6. The post-exposure unit according to claim 1, wherein the at least one radiation sensor is connected to a control unit/processing unit, wherein the control unit/processing unit is configured to monitor a captured radiation signal.

7. The post-exposure unit according to claim 6, wherein the control unit/processing unit is configured to signal deviations of the radiation signal from a predefined expected value.

8. The post-exposure unit according to claim 1, wherein the at least one radiation sensor and the at least one radiation source are connected to a control unit/processing unit, wherein the control unit/processing unit is configured to control the radiation source on the basis of a radiation signal captured by the radiation sensor.

9. The post-exposure unit according to claim 8, wherein the control unit/processing unit is configured to control the radiation source on the basis of a radiation intensity and/or radiation wavelength captured by the radiation sensor.

10. The post-exposure unit according to claim 8, wherein the control unit/processing unit is configured for regulating the radiation intensity and/or radiation wavelength respectively to a target value.

11. The post-exposure unit according to claim 1, wherein a plurality of radiation sensors is configured to capture the radiation emitted by the radiation source in different directions.

12. The post-exposure unit according to claim 11, wherein radiation sensors of the plurality of radiation sensors are arranged in a row.

13. The post-exposure unit according to claim 12, wherein the radiation sensors of the plurality of radiation sensors are arranged in at least two rows.

14. The post-exposure unit according to claim 13, wherein the at least two rows of radiation sensors form a grid of radiation sensors, wherein the grid comprises at least three rows in each dimension of the grid.

15. The post-exposure unit according to claim 1, wherein the radiation sensor or the plurality of radiation sensors is fixed relative to the receiving space and/or the radiation source.

16. The post-exposure unit according to claim 1, wherein the radiation sensor or the plurality of radiation sensors or at least one radiation sensor of the plurality of radiation sensors is moveable relative to the receiving space and/or the radiation source.

17. Equipment for post-processing a body manufactured using an additive manufacturing method from a substance curable by radiation using a post-exposure unit according to claim 1, comprising: a transport device comprising a drive for moving a build platform relative to the post-exposure unit.

18. A method for post-exposure of a body manufactured using an additive manufacturing method from a substance curable by radiation using a post-exposure unit according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The invention is explained in more detail in the following using preferred, non-limiting exemplary embodiments with reference to the drawings.

[0058] Shown are:

[0059] FIG. 1 schematically a post-exposure unit according to the invention for post-exposure of a 3D printed body;

[0060] FIG. 2 schematically a detailed sketch of a circuit board which can be used in the device according to the invention;

[0061] FIG. 3a schematically an exemplary intensity diagram for FIG. 1 and FIG. 3b an exemplary radiation angle of a possible radiation source;

[0062] FIG. 4 schematically a calibrated intensity profile as an example for FIG. 1;

[0063] FIG. 5 schematically the device from FIG. 1 having different contaminations on the surface of the receiving basin;

[0064] FIG. 6 schematically an exemplary measurement signal in the event of contamination and representation of the actual target value;

[0065] FIG. 7 schematically the device from FIG. 1 with a time-resolved and spatially resolved intensity measurement and a diagram with measured values of the intensity;

[0066] FIG. 8 schematically the device from FIG. 1 having a detached component in the receiving basin;

[0067] FIG. 9 schematically an exemplary aging curve of a radiation source as a function of the operating hours;

[0068] FIG. 10 schematically the device from FIG. 1, the spatially resolved intensity being set to a target value;

[0069] FIG. 11 schematically a device according to the invention in which the radiation source is regulated as a function of the temperature;

[0070] FIG. 12a schematically a diagram which shows the intensity of the radiation source as a function of the temperature;

[0071] FIG. 12b schematically a diagram with a temperature compensated radiation source behavior;

[0072] In the illustrated figures, parts of the device that do not serve to describe the respective figure have been omitted for the sake of clarity.

DETAILED DESCRIPTION

[0073] FIG. 1 shows a post-exposure unit 1 for post-exposure of a body 2 (see. FIG. 7) that hangs on a build platform 3, the post-exposure unit 1 comprising a receiving basin 4, a plurality of circuit boards 5, 6 and radiation sources 7 and radiation sensors, that are attached to the circuit boards 5, 6 and are connected via a control unit/processing unit 9. The intensity of at least one radiation source 7 is respectively captured on the opposite circuit board 5, 6 and by at least one radiation sensor 8 located thereon. As a result, the radiation intensity in the chamber 10 or at least one radiation source 7 can be captured, set or calibrated. This calibration can take place after a certain period of time and/or before each post-exposure process. The control unit/processing unit 9, for this purpose, is able to readjust the at least one radiation source 7 in accordance with the measured radiation intensity. When using LEDs as a radiation source, this can be done via the LED current. The intensity of the light sources 7 is measured here by respectively opposing radiation sensor 8.

[0074] FIG. 2 shows a circuit board 5 which can be used, for example, in the post-exposure unit 1 and which is equipped with a plurality of radiation sources 7 and radiation sensors 8. Each radiation source 7 has at least one radiation sensor 8 or, optionally, a plurality in order to increase the local measurement resolution.

[0075] FIGS. 3a and 3b schematically show a calibration result matching the exemplary structure from FIG. 1. FIG. 3a shows the individual measured value curves captured at the radiation sensors 8 after a certain period of time. An expected radiation intensity can be inferred on the basis of the position of the radiation source from the angle-dependent radiation behavior of the radiation source depicted in FIG. 3b. A radiation behavior of an LED was assumed in FIG. 3b. The intensities measured at the sensors 8 allow conclusions to be drawn about the radiation angle, the status of the radiation source, etc.

[0076] A calibration result based on the example shown in FIG. 1 is depicted schematically in FIG. 4.

[0077] FIG. 5 shows the post-exposure unit 1 according to FIG. 1 after at least one post-exposure process in which there has been contamination 11 of the receiving basin 4, wherein the contamination 11 prevents and/or hinders the homogeneous illumination of the chamber 10 and thus it can no longer be guaranteed that, in a renewed post-exposure process, the body to be exposed can be completely cured in the time period specified by the control unit/processing unit 9 according to the specifications for the corresponding material. As a result of the contamination 11 at least in parts of the receiving basin 4, as is depicted by way of example in FIG. 5, a lower value than a target value is measured on the opposite side of at least one radiation sensor B. The target value can correspond to the calibration value. If this is the case, an output can take place via the control unit/processing unit 9, the output informing the user of the unit 1 about the error that has occurred and optionally, requesting that the receiving basin 4 be cleaned. This allows additional process reliability and ensures that contamination of the post-exposure unit 4 for a given post-exposure duration and intensity cannot negatively influence the curing process or even prevent it completely in the case of severe contamination.

[0078] FIG. 6 shows a diagram in which the radiation intensity I.sub.cal to be achieved is plotted when there is no contamination. I.sub.cal represents the reference value that should be reached before each exposure process. The measured value represents a possible measured value in the event of a certain contamination of the receiving basin 4 (as shown, for example, in FIG. 5). If an I.sub.cal is not reached, an error message can be output via the control unit/processing unit 9 and/or an attempt can be made to increase the radiation intensity of the radiation sources 7 at least in certain regions so that I.sub.cal is reached.

[0079] FIG. 7 shows the post-exposure unit 1 according to FIG. 1 with a body 2 which is introduced into the post-exposure unit 1 and which hangs on a build platform 3. The radiation sources 7 here can be used in combination with the radiation sensors to detect the presence of a body 2 in the post-exposure unit 1, as shown. The shadowing at the radiation sensors 8 is captured differently here, depending on the geometric form of the body 2. In the example depicted in FIG. 7, a radiation sensor 8 is completely shaded and no measured value can be captured in order to be able to be compared with a previously captured target value. The target value here can come from the calibration of the chamber as was depicted in FIG. 1.

[0080] A print result can optionally also be checked based on the shadow cast, for example, whether the captured contour of the body corresponds to an expected contour. For this purpose, one or a plurality of movable radiation sources and/or movable radiation sensors can optionally be provided (for example, linearly movable or pivotable or rotatable about the receiving space).

[0081] The detachment of a body 2 from the build platform 3 is shown as an example in FIG. 4. A local change in the body 2 during and/or after the post-exposure process can thereby be detected through the difference in the shadow cast by the body 2, for example, in comparison to the case depicted in FIG. 7. An output can be made to the user in order to manually remove the body 2 from the receiving basin 4 based on detecting the detachment of the body 2 during the post-exposure process. This ensures additional process reliability and prevents a collision (crash) when a new body is introduced into the receiving basin 4.

[0082] FIG. 9 shows an exemplary course of the decrease in intensity over the operating time of a radiation source 7. An LED is assumed here as the radiation source 7 as an example. At the beginning, the radiation source has an intensity I.sub.new which drops to the value I.sub.aged after a certain number of operating hours t.sub.old. The current intensity value of the radiation source 7 can be captured together with the operating hours by using at least one radiation sensor 8. This allows conclusions to be drawn about the expected service life of the radiation source 7 and/or being able to detect a failure of a radiation source 7 and thus contributing to an increase in process reliability.

[0083] FIG. 10 shows the post-exposure unit 1 as before in a sectional illustration, the entire post-exposure unit 1 being calibrated when the build platform 3 is not equipped. In this case, all the radiation sources 7 that are present are switched on either simultaneously and/or individually and/or sequentially and while the measured values are captured by the opposite radiation sensors 8.

[0084] The post-exposure unit 1 can also be heated in the example depicted in FIG. 11. The increase in the temperature in the receiving basin 4 serves, for example, to accelerate the curing process or to provide support by activating additional, unused initiators in the body 2. An increase in the temperature in the post-exposure unit 1 leads to a change in the operating point of the radiation source 7 and thus to a radiation behavior of the at least one radiation source 7 that is a function of the temperature. To compensate for this, the intensity value can be captured on at least one radiation sensor 8 and this can be kept constant when the temperature increases by regulating the intensity of the radiation source 7. This can be done by tracking the LED current when using a LED as the radiation source 7.

[0085] This is also advantageous since the radiation source 7 itself can lead to an increase in the temperature in the post-exposure unit 1, that is, even without the presence of a heater. A decrease in intensity of the radiation source 7 ever the exposure period can thus be compensated for in this case too.

[0086] FIG. 12a shows the course of the temperature in the post-exposure unit 1, the light intensity emitted by the radiation source 7 falling as the temperature rises. This therefore leads to the fact that less radiation intensity than specified can arrive at the body 2 and the post-exposure time is therefore not sufficient to cure the body 2 to the end. This can distort the component properties and lead to production errors. In order to prevent this, the radiation values captured by the radiation sensor 8 can be used to readjust the radiation sources 7 that were built into the post-exposure unit 1. The readjustment here is carried out so that the light intensity is kept constant as the temperature rises. This can be achieved, for example, in LEDs that can be used as radiation source 7, by regulating the LED current.

[0087] The following variants and advantages can optionally be achieved with the present disclosure: [0088] LED sensor controlled post-exposure unit [0089] At least one sensor per panel (measurement of light intensity, LED aging/contamination) [0090] Measurement of the irradiation power of each panel by the opposite panel [0091] Measurement of the homogeneity of each panel and readjustment [0092] Combination of a plurality of wavelengths to achieve a broader wavelength range [0093] Calibration of the light output power [0094] Compensation for LED degeneration [0095] Efficient cooling/temperature control to improve the performance stability of the LEDs [0096] Calibration at every power-on [0097] Measurement of the shadows cast by generated bodies [0098] Measurement of whether the generated body is present in the box (shadow) [0099] Clustering of the LEDs [0100] Measurement of the contamination of the glass during calibration [0101] Measurement of contamination that has just occurred during the exposure [0102] Individual irradiation as a function of occupancy of the build platform

Further General Embodiments

[0103] 1. A device for post-exposure of a body 2 manufactured by means of an additive manufacturing method from a substance curable by radiation, the device comprising a receiving basin 4 for protecting the at least one radiation source and the at least one radiation sensor 8, the device further comprising a build platform 3 which is carrier of the body 2, characterized in that an at least partially closed chamber 10 is formed, the chamber 10 comprising a receiving basin 4 which can be irradiated by at least one radiation source 7 and further comprising at least one radiation sensor 8 which is placed in such a way that it is able to capture the radiation emitted by the radiation source 7 and to transfer it to a control unit/processing unit 9.

[0104] 2. The device according to embodiment 1, characterized in that the radiation sensor 8 is connected to a control unit/processing unit 9 which is configured to process the measured value captured by the radiation sensor 8.

[0105] 3. The device according to embodiment 2, characterized in that at least one radiation sensor 8 is connected to at least one radiation source 7 via the control unit/processing unit 9 and the intensity of at least one radiation source 7 can be controlled.

[0106] 4. The device according to any one of the embodiments 1 to 3, characterized in that a change in the state of the chamber 10, for example, from a defined calibration value, can be captured with the help of at least one radiation sensor 8, and appropriate measures can be taken via the control unit/processing unit 9.

[0107] 5. The device according to embodiment 2 and embodiment 4, characterized in that at least one radiation sensor 8 for capturing the radiation from at least one radiation source 7 is arranged opposite thereof.

[0108] 6. The device according to any one of the embodiments 1 to 5, characterized in that the chamber 10 can be closed by a build platform 3 which carries at least one body 2.