EP4334062A1

EP4334062A1 - Method and device for removing supporting structures from an object

Info

Publication number: EP4334062A1
Application number: EP22723967.0A
Authority: EP
Inventors: Gerald Resch
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-05-07
Filing date: 2022-05-05
Publication date: 2024-03-13
Also published as: AT524995A1; WO2022232859A1; AT524995B1; CA3215652A1

Abstract

A device for removing supporting structures (1, 1.1-1.13) from an object (2), wherein the object (2) is an object (2) produced by an additive manufacturing process, and wherein at least one supporting structure (1, 1.1-1.13) is provided in the object (2), between a first element (3) and a second element (4) of the object (2), the supporting structure in each case having at least one connection (5) to the first element (3) and to the second element (4) and forming a vibration system (6, 6.1-6.7) together with said elements, wherein the device (100, 101) has at least one mechanical actuator (10) which is coupled to the object (2) for introducing a mechanical excitation vibration, and wherein the device (100, 101) has a controller (18) which is coupled to the at least one actuator (10) and is programmed to control the excitation vibration and to excite the vibration system (6, 6.1-6.7) with at least a resonant vibration associated therewith in such a manner that at at least one point in time the deflection of the resonant vibration exceeds the loading limit at at least one point in the vibration system (6, 6.1-6.7), characterized in that the first element (3) has a desired structure or an intermediate plate and the second element (4) of the object (2) has a base plate (7) of the object (2), and in that the device (100, 101) has a plurality of actuators (10) which are connected to the controller (18) and are mechanically coupled to the object (2), wherein the controller (18) is programmed to introduce a plurality of excitation vibrations into the object (2), said excitation vibrations being superimposed on the resonant vibration in the vibration system, with at least one of the actuators (10) being coupled to the first element (3).

Description

Method and device for removing support structures from an object

The invention relates to a method and a device for removing support structures from an object, which was produced by an additive manufacturing process and in which at least one support structure is provided between a first element and a second element of the object and has at least one connection with each of them and in which the support structure forms an oscillating system together with the first and second element, at least one of the connections being released by excitation of the oscillating system by means of mechanical oscillations.

Furthermore, the invention relates to a method for producing an object by additive manufacturing, in which the object has at least a first and a second element, which are spaced apart from one another by a free space, and in which at least one connection between the first element or The second element and at least one supporting structure are provided and in which at least one of the connections is released after the additive manufacturing of the object by introducing mechanical vibrations.

State of the art

In the context of additive manufacturing processes, such as 3D printing of plastics, metals or concrete, laser sintering, build-up welding or the like, there is often a need to provide support structures or auxiliary structures, for example in order to be able to realize free-standing or overhanging structures. Without the use of appropriate support structures, for example, horizontal elements without underlying structures could not be realized using 3D printing.

These support structures or auxiliary structures can also be used, for example, for heat transport and/or for mechanical support, stabilization or shaping. The support structures are usually removed as the last processing step, but this is often not possible or only possible to a very limited extent, especially in the case of internal structures or very small structures.

In the case of welding/surfacing, too, shaping or maintaining the shape is occasionally made possible or facilitated by auxiliary structures.

The importance of support structures is greatest in 3D printing, where the use of support structures limits the manufacturability of objects or shapes. the The profitability of the 3D printing process also depends to a large extent on the efficient removal of the support structures.

Support structures play a particularly important role in 3D printing, especially in its sub-area that is based on gluing or fusing or sintering of material, and especially in metal-based 3D printing. Due to the high temperatures for the local melting of the material during laser sintering, thermal stresses in particular occur in the components or objects. In order to suppress the resulting deformations, support structures are sometimes unavoidable. On the one hand, they keep the building components in shape and position, on the other hand, they are essential for heat transport and temperature equalization. However, the labor cost of removing the support structures is typically over half the labor cost associated with production. As a result, the economics of such a manufacturing process is severely limited.

In large-format 3D printing, especially in the construction industry, according to the state of the art, the difficulty in removing auxiliary structures also plays a dominant role in the manufacturing costs and the efficiency of the process.

With nano 3D printing (FEBID and FIBID), the size of the structures that can be produced is limited by a maximum overall height, which can only be increased through the use of (printed) supporting structures.

It is known from the prior art, for example, to remove such support structures by manual removal (e.g. by means of grinding, sawing, milling, melting and knocking out, etc.). However, such a removal is associated with high costs due to the large amount of work involved. In addition, some very small or internal support structures or those that are difficult to access are very difficult to remove manually.

The prior art (WO 2018/093958 A1) discloses methods for removing support structures from 3D-printed objects made of metal (“selective laser sintering”). Support structures are used during printing to support any free-hanging areas. After printing, the articles are then sonicated to remove the support structures using an ultrasonic device with the article fully immersed in a liquid. In this case, longitudinal ultrasonic waves of a specific frequency are used to remove the support structures, with an ultrasonic sensor being attached to the support structure, which records the resonance of the support structure while the entire component is subjected to the ultrasonic waves. The frequency of the ultrasonic waves is modified until the maximum resonance of the support structure is found, ie the resonance frequency of the support structure is reached. Such a method, using a liquid as the transmission medium without taking any further countermeasures, suffers from a number of disadvantages.

Above all, the liquid drastically reduces the quality of the resonance vibrations of the support structures through mechanical damping (the quality is often reduced by a factor of more than 100, not infrequently by a factor of well over 1000). This has decisive disadvantages for the excitation of the resonant vibrations. On the one hand, with constant resonance excitation, the amplitude increases correspondingly low, since at the same time energy flows out of the vibration system due to damping, which significantly reduces the efficiency of the method. On the other hand, the excitation energies required to release the connections and remove the support structures are very high, which in turn leads to damage to other sensitive target structures.

When using ultrasound, cavitations can also occur, which can damage fine target structures, which reduces the usability of the method for very fine structures. Furthermore, one is only limited to longitudinal waves, which further restricts the spectrum of vibrational modes that can be excited.

Furthermore, the liquid can cause undesired chemical interactions with the material of the object and damage it. For very large parts, positioning them in a suitably large container is impractical and expensive, if not impossible.

Methods of this type therefore fundamentally suffer from the fact that the supporting structures can hardly be broken in a targeted and selective manner without correspondingly damaging other sensitive structures of the component itself.

Disclosure of Invention

The object of the present invention is to improve a method for removing support structures from an object that has been produced by an additive manufacturing process in such a way that the support structures can be removed efficiently and safely without damaging the elements of the object itself.

The invention solves the problem set by a method for removing support structures with the features of claim 1 and a device with the features of claim 11. Advantageous refinements of the invention are set out in the dependent claims, the description and the drawings. The method according to the invention and the device according to the invention relate to the removal of support structures from an object which was produced by an additive manufacturing process and in which at least one support structure is provided between a first element and a second element of the object and has at least one connection with each of them and in which the support structure forms an oscillating system together with the first and second elements. According to the method, at least one of the connections is released by exciting the vibration system by means of mechanical vibrations, with at least one mechanical excitation vibration being introduced into the object by means of at least one actuator, which is coupled to the object, and fed to the vibration system and the vibration system with at least one assigned to it resonance vibration is excited in order to release the at least one connection, wherein at least one point in time the deflection of the resonance vibration exceeds the load limit at at least one point in the vibration system, the first element being a target structure or an intermediate plate and the second element of the object being a base plate of the The subject is and the at least one actuator is coupled to the first element.

At least one point in the sense of the present invention is a point of spatial expansion that is part of the object and is formed in particular by a spatial arrangement or a spatial area of related and adjacent points in the object. In particular, the point is in a connection between a first or second element and a support structure. As a rule, the load limit is exceeded in an area of associated points or locations in the connection, so that the connection between the support structure and the first or second element is completely released.

Since at least one mechanical excitation vibration is introduced into the object and the vibration system is excited by the excitation vibration with a resonance vibration, a high local deflection or amplitude of the resonance vibration in the vibration system can be achieved. In particular, the frequency of the excitation vibration is in the vicinity of a resonance frequency or natural frequency of the vibration system in order to enable efficient excitation of the resonance vibration.

By excitation of the resonance oscillation with an excitation frequency (frequency of the excitation oscillation) which essentially corresponds to a natural frequency of the oscillation system, the energy of several excitation oscillations can be collected in the resonance oscillation if the quality Q is sufficiently high or the damping I) is low. This leads to an increase in resonance of the resonance oscillation and very high deflections or amplitudes can be achieved. Through the continuous Collecting the energy from the excitation vibration, the resonance vibration preferably has the highest energy density in the entire object at least at a point in time at the point of the connection to be released.

If the deflection or amplitude of the resonance vibration at a point in time exceeds the load limit of the support structure at at least one point in the object, in particular at a point of the connection, the energy collected from the excitation vibration will result in a resonance catastrophe and the at least one connection between the support structure and a first or second element of the object is solved according to the invention.

In other words, a method for removing support structures from an object is shown which was produced using an additive manufacturing method, in particular a primary shaping method, preferably a 3D printing method, particularly preferably using a 3D printing method for metals , whereby the support structures are removed or broken open by mechanical stimulation. For this purpose, energy is fed from several actuators in the form of excitation vibrations to the support structures and collected or stored in them, whereby the vibration amplitude in the support structure is increased until the support structure breaks or the support structure is connected. According to the invention, at least one vibration parameter (deflection, energy, etc.) at least at one point of the at least one support structure to be broken up exceeds the corresponding value of the excitation vibration at the point of generation or coupling into the object. The excitation vibrations, the energy of which is added up, can come from one or more actuators, which affects, among other things, the number of vibrations to be collected until the overload limit is reached at one point on the support structure.

With regard to the resonance vibration, the vibration system preferably has a quality Q of greater than or equal to 1/2, in particular greater than or equal to 2, particularly preferably greater than or equal to 10.

The quality of the vibration system is decisive for the ability of the resonance vibration to collect energy from the excitation vibrations and thus to lead to a resonance increase of the amplitude in a location-selective manner. The quality Q is defined via the damping I) of the system as Q = 1 / 2D. In order to achieve high quality in the vibration system, the vibration system must therefore have the lowest possible damping. Numerous influencing factors contribute to the damping of the resonance vibration, such as the medium surrounding the support structure, the connections between the support structure and the first or second element of the object, as well as other vibration systems in the Item of high quality. As a further consequence, the damping also leads to a shift and broadening of the resonance, with the natural frequency of the resonance vibration being shifted by the factor (1 −D ² ) ^m with damping compared to the undamped natural frequency.

According to a preferred embodiment variant of the invention, the excitation frequency of the excitation oscillation is selected such that the resonant frequency of the oscillation system is sufficiently excited, but there is no resonant excitation of other oscillation systems in the object.

The vibration system within the meaning of the invention is the system comprising at least the first and second element and the support structure to be removed in the object, with the support structure being connected to the first and second element by at least one connection. Such a connection can be a materially bonded connection, such as is formed in the course of an additive manufacturing process. In a further embodiment variant of the invention, such a connection can also be a non-positive connection, with the support structure being clamped between the first and second element, for example, or an element being loaded on the support structure.

Those structures of the object which remain in the object after removal of all temporary elements, such as in particular the support structures, are referred to as target structures. A base plate can be a flat surface, for example, on which the object is formed, from which the object is detached again after completion or after the method in question has been carried out. The method according to the invention is thus suitable for the reliable and selective removal of all types of support structures that are temporarily provided between any elements of the object.

An intermediate element is an element that is spaced from the target structure and from a base plate by support structures.

In particular, the resonance vibration associated with the vibration system corresponds to the excitation of at least one natural mode of the vibration system. The at least one natural mode of the vibration system can preferably be a deformation vibration of the support structure. A deformation vibration can be understood as meaning a bending vibration, a stretching vibration, a rotational vibration or the like.

In one embodiment of the method according to the invention, a single actuator is coupled to the first element and introduces a mechanical excitation vibration into the first element, with which it causes the first element to resonate, whereupon the Actuator changes the excitation vibration to a counter-vibration and thereby supports the cancellation of the support structure.

In a further embodiment variant of the invention, several actuators can be coupled to the first element and optionally to the second element and introduce several mechanical excitation oscillations with different excitation frequencies. In this way, each of the excitation vibrations can stimulate a different resonance vibration and thus a different natural mode of the vibration system. The resonant vibrations of the vibration system are superimposed to form a resulting overall vibration, which, for example, can have a stretching vibration and a rotational vibration at the same time. A more efficient release of the at least one connection of the support structure can be achieved by the simultaneous excitation of several resonant vibrations, wherein the amplitudes of the individual excitation vibrations can be reduced and the risk of damage to target structures is reduced.

The excitation frequencies of the several excitation oscillations are preferably not in any rational relationship to one another. In this case, the quotient of the excitation frequencies is preferably an irrational number, so that an excitation of the same resonance oscillation by a plurality of excitation frequencies is avoided.

In a further embodiment variant of the invention, several actuators can be coupled to the object and introduce several excitation oscillations into the object with essentially the same excitation frequencies. The excitation vibrations can preferably be constructively superimposed on the resonance vibration in the vibration system at the location of the support structure, whereby the amplitude of the resonance vibration in the vibration system can be increased in a simple manner and the release of the connection can be further facilitated. In one embodiment of the invention, at least one actuator is attached to the base plate of the object and the actuators attached to the first element and to the base plate have the same or a similar excitation frequency, with similar excitation frequencies being related by a maximum of 10% the smaller excitation frequency differ from each other. The excitation by the actuators should be synchronous, i.e. with the same or similar phase position, with a similar phase position meaning a phase difference of maximum 15°.

If the actuators are also coupled to the object at different locations, the reliability of the method can be further increased. In particular, if the phase shift of the excitation vibrations introduced into the object is adjusted in such a way that the excitation vibrations have the same phase at the location of the support structure have and thus overlap constructively. In this way, the excitation of other structures or elements in the object can be avoided, since the excitation oscillations are constructively superimposed only at points of the same phase and cancel out or weaken one another in the remaining area of the object.

According to a further embodiment variant of the invention, at least one actuator is attached to a support structure of the object. By attaching this actuator directly to a support structure of the object, the efficiency of the coupling between the actuator and the object and the introduction of the excitation vibrations into the vibration system can be improved.

In a preferred embodiment of the present invention, the at least one mechanical actuator is directly mechanically coupled to the object, i.e. the mechanical coupling between the actuator and the object does not take place via a fluid as an indirect vibration transmitter. By introducing the mechanical vibrations directly into the object via the actuator, unfavorable damping by a possible fluid can be avoided and the vibration quality can thus be significantly increased.

In a further preferred embodiment variant, the object can be freely suspended or kept freely floating during the method. In this way, damping components in the vibration system and a discharge of vibration energy from the support structure into the damping can be avoided. Such a free suspension can take place, for example, by decoupling the object via elastic buffers, air cushions, etc., or by suspending it by means of springs, ropes, or the like. It is also conceivable that the object is held magnetically floating, for example. The suspension can preferably be designed such that the resonant frequencies of the suspension itself are at a sufficient distance from the resonant frequencies of the vibration system of the support structure and thus no resonant excitation of the suspension occurs as a result of the excitation vibration. The achievable quality of the resonance vibration in the vibration system can thus be at least 100, preferably at least 1,000, particularly preferably at least 10,000.

Furthermore, if the actuators are connected to a control device via electrical lines, these electrical lines can be designed in such a way that they only add very little damping to the suspension. For this purpose, the electrical lines can consist, for example, of very thin wires made of flexible strands (e.g. braided strands), or in a further embodiment variant the control device can be provided directly together with the actuators. Furthermore, the controller and the actuators could be supplied with wireless energy supplies (e.g. by means of batteries), so that no electrical lines are necessary to the outside, which exert additional damping on the suspension. In yet another embodiment variant, the controller can communicate wirelessly with the actuators (for example by radio, by wireless network, by optical signal transmission or the like).

In a further embodiment variant, in addition to excitation of the vibration system with the at least one resonant vibration, a mechanical pulse can be introduced into the base plate or the support structure. While the resonance vibration is excited via the excitation vibration, the mechanical impulse can also couple into the resonance vibration and briefly increase its amplitude. The impulse can be coupled into the object, for example by means of a short, hard impact, and there it can excite a broad frequency spectrum with a high amplitude. The deflection of the support structure can exceed the breaking point in the connection and thus cause the connection to suddenly loosen.

According to one embodiment of the invention, the resonant frequency of the resonant vibration can be determined and the excitation frequency of the excitation vibration can be adjusted as a function of the resonant frequency determined, in particular in a control loop (control loop). Through continuous resonant excitation of the vibration system of the support structure or the connection to be released, this connection can harden as a result of the vibrations. The progressive hardening of the connection results in a constant shift in the resonant frequency of the associated resonance vibration, as a result of which the excitation vibration has to be tracked in order to ensure resonant excitation of the resonance vibration until the connection is released. In particular, this can prevent the excitation frequency from resonantly exciting target structure vibration systems instead of the support structure vibration system and damaging or destroying target structures as a result of shifting the resonant frequencies.

The resonant frequency of at least one resonant vibration of the vibration system can be determined continuously, for example by introducing a frequency sweep via the actuators into the vibration system as an excitation vibration and measuring the frequency response via sensors. After the resonance frequency of the resonance vibration has been determined, the excitation frequency can then be set to the determined resonance frequency and the method can be continued again with the introduction of the excitation vibration into the support structure. As a result, the most efficient possible excitation of the resonance vibration of the vibration system can always be ensured in order to ensure the most targeted possible release of the at least one connection between the support structure and the first and second element. The determination of the resonant frequency and subsequent adjustment of the excitation vibration can preferably take place continuously in a control loop, so that the method can react immediately to changes or shifts in the resonance frequency.

In a special embodiment variant of the invention, a phase-locked loop (PLL—phase-locked loop) can be used as the control loop. The phase of the excitation vibration is always adapted to the phase of the resonance vibration and tracks it. If the phases of the excitation and resonance oscillations match, then the excitation frequency also corresponds to the resonance frequency.

In one embodiment variant, the excitation oscillation can be introduced into the support structure oscillation system as a continuous sinusoidal oscillation with a specific excitation frequency. In this way, a targeted excitation of specific resonance oscillations can be achieved, but if the resonance frequency shifts, the excitation frequency must be tracked in order to continue to achieve excitation of the desired structure.

In a further embodiment variant, the excitation oscillation can also have a pulsed sinusoidal oscillation. The spatial selectivity of the resonant excitation of the resonance oscillation can be significantly increased by the time-limited sine pulse, in particular when using a plurality of actuators at the same time. By parallel transmission of wave packets from a number of actuators, which are superimposed in phase and simultaneously at the location of the support structure, the vibration energy can advantageously be introduced exclusively into the support structure vibration system. The risk of damage to target structures is also drastically reduced. A particularly efficient and reliable method for removing support structures can thus be provided.

According to a further embodiment variant, the excitation oscillation can also have band noise. Such a band noise can appear, for example, in the frequency spectrum as a Gaussian curve with a mean value at the nominal excitation frequency. The width at half maximum (FWHM) of the Gaussian curve or the normal distribution determines the width of the band noise. In the case of third-octave noise, the width corresponds, for example, to one third of the excitation frequency or the mean value. The use of band noise as the excitation oscillation can be characterized in particular by a lower susceptibility to frequency shifts in the resonance oscillation. For example, when there is a shift by the full width at half maximum, an excitation with half the maximum excitation amplitude can still take place.

According to yet another embodiment variant, the excitation oscillation can have a frequency sweep. In the context of the present invention, a vibration with a frequency that changes over time is understood as a frequency sweep, with the change in the Frequency, for example, linear (linear frequency sweep), quadratic, logarithmic or the like. Can be done. By using a frequency sweep as an excitation oscillation, a change in the resonant frequency over time can be tracked, in particular without additional control technology, with the excitation frequency increasing or decreasing continuously in accordance with the frequency sweep. For example, by calculating or simulating the predicted frequency curve of the resonance vibration of the support structure, which is caused by hardening of the connection to be released, and corresponding superimposition and the predicted frequency curve with the frequency sweep, the excitation frequency can always be kept close to the resonance frequency. The frequency sweep can start at an initial frequency and continuously change towards an end frequency.

The previously mentioned embodiment variants for the excitation frequency can also be combined with one another as desired. For example, a linear frequency sweep can be combined with a continuous sine wave. Likewise, the frequency sweep can also be combined with a pulsed sinusoidal oscillation from a plurality of actuators, the excitation frequency of all time-clocked and phase-aligned pulsed sinusoidal oscillations being continuously changed in accordance with the frequency sweep. It is also conceivable that the frequency sweep is combined with band noise or with a pulsed sine wave with superimposed band noise.

The invention has also set itself the task of designing a device for removing support structures of the type mentioned at the outset more efficiently and cost-effectively.

The object is achieved by a device which has at least one mechanical actuator which is coupled to the 3-dimensional object in order to initiate a mechanical excitation vibration, the device having a controller which is coupled to the at least one actuator and which is programmed to to control the excitation vibration and to excite the vibration system with at least one associated resonance vibration in such a way that at least one point in time the deflection of the resonance vibration exceeds the load limit at at least one point in the vibration system, the first element of the object being a target structure or an intermediate plate and the second element is a base plate of the object. The device has a plurality of actuators connected to the controller and mechanically coupled to the object, with the controller being programmed to introduce a plurality of excitation vibrations into the object, which are superimposed in the vibration system to form the resonance vibration, with at least one of the actuators being coupled to the first element is. In this case, the actuator can preferably be coupled directly to the object, so that the mechanical excitation vibration from the actuator can be fed directly to the vibration system in order to stimulate the resonance vibration. The controller of the device is programmed in such a way that in particular the frequency and/or the phase and/or the amplitude of the excitation oscillation can be controlled. It can always be ensured here that the resonance vibration of the vibration system is excited, with the resonance vibration being formed by a vibration mode of the deformation vibration of the connection between the support structure and the first or second element of the object. The excitation vibration is controlled via the controller in such a way that the deflection of this resonance vibration at a point in time exceeds the load limit at a point in the vibration system, in particular the load limit of the connection, and the connection is thus released according to the invention.

According to a further embodiment variant of the invention, the device can have a plurality of actuators which are connected to the controller and are mechanically coupled to the object. The controller of the device is preferably programmed to introduce several excitation vibrations into the object at the same time, which are superimposed in the vibration system to form the resonance vibration. As described above for the method according to the invention, such a superimposition of the excitation vibrations can generate a resonance vibration with a very high amplitude at the location of the connection of the support structure to be released, which enables the connection to be released more easily and reliably.

In an alternative embodiment, a single actuator is coupled to the first element to introduce a mechanical excitation vibration into the first element, with which the actuator causes the first element to resonate, whereupon the actuator is controlled to change the excitation vibration to a counter-vibration and thereby the Cancel the support structure to support.

According to one embodiment variant of the invention, the device can have a base plate to which the at least one actuator is rigidly connected and directly coupled. The object with the support structure to be removed can be positioned on the base plate, which enables direct and efficient introduction of the excitation vibration into the vibration system. In a further embodiment of the invention, the base plate can also be used to manufacture the object. The object is manufactured directly on the base plate including the support structure using an additive manufacturing process (e.g. 3D printing). Targeted control of the actuator by means of the control of the device allows the support structure to be removed in a targeted and efficient manner without further preparatory steps after production. According to a further embodiment variant of the invention, the multiple mechanical actuators can be arranged along at least one side of the base plate. The base plate preferably has a peripheral edge area and a central positioning area, with the positioning area being designed to accommodate the object and the mechanical actuators being arranged in the edge area of the base plate. A device that can be used in a particularly versatile and flexible manner can thus be provided.

In a further embodiment variant, the mechanical actuators can be in the form of piezo actuators which are coupled to the object in a non-positive manner. Piezo actuators can be particularly suitable for introducing higher-frequency excitation vibrations into the object.

In yet another embodiment variant, the mechanical actuators can be in the form of electrodynamic actuators which have an electrodynamically linearly oscillating mass. The electrodynamic actuator can be designed similar to a loudspeaker or a bass shaker (structure-borne sound transducer) for generating low-frequency vibrations. In addition, such actuators, like piezo actuators, can simultaneously emit several frequencies largely independently of one another.

In yet another embodiment variant, the mechanical actuators can be in the form of electrodynamic actuators which have an electrodynamically rotatable mass and/or imbalance. The rotatable mass or imbalance in turn introduces an excitation vibration into the object that is non-positively coupled to it. Such electrodynamic actuators are particularly suitable for introducing medium- to low-frequency excitation vibrations into the object with a particularly high level of efficiency.

In a further embodiment variant, the device can have a pulse generator. Such an impulse generator can exert an additional excitation on the object by means of a hard blow with a high impulse, which, in addition to the excitation vibration, can contribute to a sudden release of the connection.

According to one embodiment variant, the controller has a measuring device for measuring the resonant frequency of the resonant vibration and a control device for controlling the excitation frequency of the at least one excitation vibration. The measuring device is connected to the control device and the control device is set up to adapt the excitation frequency as a function of the resonance frequency. In this way, the device can reliably respond to changes in the resonant frequency, for example due to Hardening of the connection to be released as a result of the excitation, react and adjust the excitation frequency of the excitation vibration accordingly.

In one variant, the control device can have a control loop, which can be embodied, for example, as a phase-locked loop (PLL—“phase-locked loop”). The control loop or the phase-locked loop can reliably adapt the excitation oscillation in such a way that it essentially always corresponds to the resonant frequency.

The controller of the device is also preferably programmed to carry out the method according to the invention.

The invention has also set itself the task of providing a method for producing an object by means of additive manufacturing of the type mentioned at the outset, which enables reliable production of an object using support structures and the subsequent removal of these support structures.

The invention solves the problem in that the support structure is designed during additive manufacturing in such a way that an oscillating system consisting of the first and second element and the supporting structure is formed, the oscillating system having at least one resonant oscillation in relation to the supporting structure, the predetermined resonant frequency of which is lower is as the resonant frequencies of resonant vibrations related to the first or second element.

If the vibration system exhibits a resonant vibration whose resonant frequency is lower than the resonant frequencies related to resonant vibrations of the first or second element, resonant excitation of structures other than those to be removed can be avoided in a reliable manner. In particular, it can be ensured that only the connection between the support structure to be removed and the first or second element is released by resonant excitation and the remaining target structures of the object are not damaged.

In this case, the predetermined resonant frequency of the resonant vibration in relation to the support structure is preferably lower than the resonant frequencies in relation to the first or second element. The lower frequency further reduces the probability of resonant excitation of other target structures in the object. In particular, the specified resonant frequency is a specified tolerance range below the resonant frequencies related to the first or second element, since in particular due to resonant excitation of the support structure or the connection, its resonant frequency can increase due to hardening, as a result of which the distance to the resonant frequencies of the target structures decreases, the resonant frequency but still within the tolerance range. A A particularly reliable method for manufacturing objects can thus be provided.

According to a further embodiment variant of the invention, a support can be provided between the first element and a further element or between the second element and a further element of the object. The support can preferably further increase the resonant frequencies of the resonant vibrations in relation to the first element or in relation to the second element and thus further increase their distance from the resonant frequency in relation to the support structure.

In one embodiment variant, the at least one support structure can be designed in such a way that its connection to the first and/or second element has a predetermined breaking point. If a predetermined breaking point is provided in a connection, i.e. at the transition from the support structure to the first or second element, then on the one hand the associated resonance frequency can be further reduced and on the other hand a weak point with a low load limit or with a low breaking limit can be installed at which the connection already breaks at Excitation with low resonance vibration amplitudes fails and dissolves.

The predetermined breaking point can be designed, for example, in the form of a cross-sectional narrowing and/or a sharp edge. A cross-sectional narrowing can be formed, for example, by an hourglass shape or, for example, have a cone shape, the tip of which represents the cross-sectional narrowing. Alternatively, the predetermined breaking point can also be formed by an edge, which can make it easier to loosen the connection.

In a preferred embodiment variant, the resonant vibrations of the elements without support structures can be determined on the basis of the object to be produced and the support structure can be designed in such a way that the at least one resonant vibration of the support structure vibration system has a resonant frequency in relation to the support structure that is lower than the lowest resonant frequency of the resonant vibrations of the elements of the object without support structures.

In one embodiment variant, such a determination of the resonant vibrations or the associated resonant frequencies of the elements of the object without support structures can be carried out, for example, by computer simulation or calculation based on the design drawings and data. A Fourier analysis of all frequencies in the object can be carried out by means of computer simulation or calculation.

In an alternative embodiment variant, the resonant vibrations or the associated resonant frequencies of the elements of the object can be determined without support structures by measuring the resonant frequencies on a prototype. Thereby can For example, a prototype can be made with generic support structures and the support structures are then removed by hand. Thereafter, the resonance response of the object can be determined by recording using a sensor when the object is excited, for example with a frequency sweep. The resonance spectrum in the frequency domain can be determined from the resonance response using Fourier analysis.

Based on the resonance spectrum obtained for the object without support structures, the support structure can now be designed and formed in such a way that its resonance frequency is below all resonance frequencies in the determined resonance spectrum of the object.

In a further embodiment, several support structures can be provided in several support structure vibration systems in the object, and the resonant frequencies of the at least one resonant vibration of the support structure vibration system related to the respective support structure together form a frequency band. If several support structures are provided, which are designed in such a way that their resonant frequencies together form a frequency band, the reliability of the method can be further improved. The resonant frequencies in the frequency band can be resonantly excited together, for example, by excitation using an excitation frequency, so that the method can be significantly accelerated. Advantageously, the support structures can also be designed in such a way that their resonant frequencies are all in the frequency band below the resonant frequencies of the target structures. The risk of damage to target structures can thus be further reduced.

According to a preferred embodiment variant of the invention, a method according to one of claims 1 to 11 is carried out to release the at least one connection and to remove the support structure following the additive manufacturing of the object.

Brief description of the figures

In the following, preferred embodiment variants of the invention are presented in more detail with reference to the figures. Show it:

1 shows a schematic plan view of a device for removing a support structure from an object according to a first embodiment variant,

2 shows a schematic plan view of a device according to a second embodiment variant,

3a shows a schematic cross-sectional view of a support structure according to a first embodiment variant,

3b shows a schematic cross-sectional view of a support structure according to a second embodiment variant, 4a shows a schematic cross-sectional view of a support structure according to a third

variant,

4b shows a schematic cross-sectional view of a support structure according to a fourth

variant,

5a shows a schematic cross-sectional view of support structure according to a fifth

variant,

5b shows a schematic cross-sectional view of a support structure according to a sixth

variant,

6 shows a schematic cross-sectional view of a vibration system with two support structures according to a seventh embodiment variant, and

7 shows a schematic cross-sectional view of a vibration system with a multiplicity of support structures according to further embodiment variants.

Ways to carry out the invention

The embodiment variants of the invention specifically described below are only to be regarded as exemplary embodiment variants and are not to be regarded as limiting the scope of protection as defined according to the claims.

1 shows a device 100 for removing support structures 1 from an object 2 according to a first embodiment variant. Using the device 100, a method 200 for removing the support structures 1 from the object 2 can be carried out according to the invention. Particular configurations of the method 200 result from the following description.

The object 2 is produced by an additive manufacturing process, with at least one support structure 1 being provided in the object 2 between a first element 3 and a second element 4 of the object 2 . The support structure 1 has at least one connection 5 with the first element 3 and with the second element 4 and together with these forms a vibration system 6. Such vibration systems 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7 (6, 6.1-6.7) with support structures 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 1.10, 1.11, 1.12, 1.13 (1, 1.1-1.13) between a first and second element 3, 4 are shown in detail in Figures 3a, 3b and 4-7. A detailed description of the figures mentioned is given below.

The device 100 according to FIG. 1 has a base plate 7 on which the object 2 is provided in a central positioning area 8 and is mechanically coupled to the base plate 7 . The first element 3 and/or the second element 4 of the object 2 can either be a target structure (ie a structure that is not to be removed), or else the base plate 7 itself on which the object 2 is provided.

The object 2 is an object 2 which was produced using an additive manufacturing process, for example using 3D printing or the like. The object 2 can either be provided after production in the positioning area 8 of the base plate 7 or be manufactured directly in the positioning area 8 of the base plate 7 , so that the base plate 7 can be seen as part of the object 2 . For example, in a variant embodiment, the base plate 7 can form the first element 3 of the object 2 itself. After completion of the method 200, ie after removal of the support structures 2, the object 2 can be removed or detached from the base plate 7 again.

The object 2 is shown in FIG. 1 as a transparent contour with a large number of support structures 1, it being possible for the support structures 1 to be provided at any desired locations within the object 2.

In a peripheral edge area 9 of the base plate 7 , the device 100 has a plurality of actuators 10 which are mechanically coupled to the base plate 7 and can thus introduce mechanical excitation vibrations into the object 2 .

The device 100 has an array of piezo actuators 11 in its lower edge area 9 of the base plate 7 . The piezoelectric actuators 11 can be used either as actuators 10 for initiating mechanical vibrations, or as sensors for measuring the resonance behavior or the resonance response of the object 2, depending on the control.

Furthermore, the device 100 has a row consisting of eight electrodynamic actuators 12 in its upper edge area 9 of the base plate 7 . Such electrodynamic actuators 12 (also referred to as "shakers") can also be used to introduce (predominantly low to medium frequency) excitation vibrations into the object 2 . In one embodiment variant, the individual actuators 12 can generate excitation oscillations with different excitation frequencies independently of one another. In a further embodiment variant, the actuators 12 can also be controlled together in order to generate a single excitation oscillation with a specific excitation frequency.

Furthermore, two unbalance actuators 13 are arranged on the base plate 7 in the left and right edge region 9, which in particular transmit low-frequency vibrations with high Amplitude in the object 2 can initiate. The imbalance actuators 13 each have an electric motor (in particular a servomotor with position detection), on whose shaft 14 a cross member 15 is attached, which was shown as an example for the left upper actuator 13 . An unbalanced weight 16 is provided on this cross member 15 and is preferably mounted such that it can be displaced along the cross member 15 . Preferably, the cross member 15 can be set in rotation and after reaching a predetermined target speed, the imbalance weight 16 can be displaced outwards, so that a mechanical vibration is coupled into the base plate 7 due to the imbalance. By quickly reaching the speed and the subsequent generation of the imbalance, an excitation of undesired frequencies is further prevented.

The different actuators 10 have different frequency bands in which they function particularly advantageously. Unbalance actuators 13 are preferably suitable for excitations of approximately 0-400 Hz, linear electrodynamic actuators 12 are preferably suitable for excitations of approximately 3-2000 Hz, and piezoelectric actuators 11 are preferably suitable for excitations of approximately 1 kHz-5 MHz.

In a further embodiment variant, which is not shown in detail in the figures, impulse generators can also be coupled to the base plate 7 in order to introduce a short, high impulse into the object 2 and thus a sudden release of the connections 5 between the support structure 1 and the first or second Item 3, 4 facilitate.

As further shown in FIG. 1, the actuators 10 are connected to a controller 18 via lines 17 (in particular bus lines). In particular in the case of bus lines as lines 17, each actuator 10 can be separated from the controller 18 and controlled independently. The controller 18 is programmed in such a way that a desired excitation vibration with a predetermined excitation frequency is introduced into the object 2 and the vibration system 6 of the support structure 1 is excited there with a resonance vibration assigned to it. The initiation of the excitation vibrations takes place via appropriate activation of the actuators 10.

The controller 18 is programmed in particular to carry out the method 200 described according to the embodiment variant.

The controller 18 is further designed and programmed so that the piezo actuators 11 can also be used as piezo sensors. The controller 18 can switch between the operating modes as actuator 10 and sensor as desired. A part of the piezoelectric actuators 11 can also be used as sensors. As shown in FIG. 1 , the piezo actuators 11 are arranged equidistantly in a row along the entire side of the positioning area 8 of the base plate 7 . By driving the piezo actuators 11 in parallel to emit vibrations with the same phase, a parallel wave front can be emitted and the resonance behavior of the object 2 can be determined by measuring the vibration response using piezo sensors. Thus, the device 100 can be used to find resonators in the object 2 and to determine their resonant frequency. In the sensor mode, the piezo actuators 11 can very precisely record and analyze vibrations according to location, frequency and amplitude. With a known excitation, the vibration properties, such as the vibration quality, the resonance frequency and the directions of the vibration modes, can be determined for each location on the base plate 7 .

The electrodynamic actuators 12 and the imbalance actuators 13 can also be used by the controller 18 to emit excitation vibrations with predetermined excitation frequencies.

Within the framework of the method 200, a mechanical excitation oscillation is thus generated and introduced into the object 2 by means of the actuators 10, which are connected to the base plate 7 and are thus mechanically coupled to the object 2. The mechanical excitation vibration is fed to the vibration system 6 consisting of the support structure 1 and the first and second element 3, 4, as well as the connections 5 between them, whereby the vibration system 6 is excited with an associated resonance vibration. Due to the deflection of the resonant vibration, the load limit is exceeded, in particular at the location of the connection 5 between the support structure 1 and the first or second element 3, 4, and the respective connection 5 is released.

By emitting the excitation vibration from the actuators 10 and exciting a resonance vibration of the vibration system 6, the deflection of the resonance vibration and thus of the connection 5 can at a point in time exceed the load limit at least at one point, with the connection 5 being released. In particular, the load limit is the breaking point in connection 5.

The resonant vibration assigned to the vibration system 6 corresponds to the excitation of at least one natural mode of the vibration system 6. The natural modes of the vibration system 6 that are preferably to be excited represent, in particular, deformation vibrations of the support structure 1.

In a preferred embodiment variant, as indicated schematically in FIG. 1, the controller 18 has a measuring device 19 which is designed to measure the resonant frequency of the resonant vibration. The controller 18 also has a control device 20 on, which is designed to regulate the excitation frequency of the at least one excitation oscillation. The measuring device 19 can use the signals from the piezoelectric actuators 11 to measure the resonant frequencies, while the control device 20 controls the actuators 10 to generate the excitation vibration with an excitation frequency determined by the control device 20 . The measuring device 19 is connected to the control device 20 and the control device 20 is set up to adapt the excitation frequency as a function of the resonance frequency determined by the measuring device 19 . According to one embodiment variant, the control device 20 can be embodied as a control loop (PID) or phase-locked loop (PLL) in order in particular to track changes in the resonance frequency in the excitation frequency.

The signal form of the excitation oscillation can be determined by the controller 18 as a function of the support structures 1 to be removed or to be excited. For example, the excitation oscillation can have a continuous sinusoidal oscillation at a predetermined excitation frequency in order to achieve cyclical excitation and charging of the resonance oscillation. Likewise, the excitation oscillation can have a pulsed sinusoidal oscillation or a band noise or a frequency sweep. By means of these signal forms or any combination thereof, for example, the resonant vibrations can be excited and measured simultaneously.

The method 200 can, for example, run in several passes, corresponding to item 2 in FIG. 1 . Thus, in a first pass, the support structures 1 shown vertically are broken off, with the support structures 1 shown horizontally remaining connected to the object 2 and holding or stabilizing it. In a second pass, the remaining support structures 1, which are shown horizontally, are then broken off.

While the method 200 is being carried out, the device 100 hangs on the base plate 7 at four suspension points, in particular on its corners, which, however, is not shown in more detail in the figures. The suspension consists of 4 thin elastic ropes or cords (e.g. made of an elastomer). In a preferred case, the resonant frequency of the suspension can be less than 1 Hz, preferably less than 0.5 Hz, particularly preferably less than 0.25 Hz. The length or tension of the suspension can also be adjusted by motorized, controllable winches in order to keep the device 100 horizontal.

According to a further embodiment variant, the entire device 100 is located in an evacuatable chamber, which, however, is also not shown in the figures. With that you can Need to be increased by reducing the air friction, the quality of the resonance vibrations. The actuators 10 are preferably designed for use in a vacuum. In an alternative embodiment variant, the chamber can be filled with a suitable gas, for example in order to optimize the quality of the resonance vibrations and the heat dissipation capability of the actuators 10 at the same time. For example, a gas is used at a pressure that combines good thermal conductivity with low viscosity (eg, helium at less than atmospheric pressure).

In alternative embodiment variants, which are not shown in more detail in the figures, the object 2 can also be freely suspended or kept freely floating during the method 200 without the use of a device 100 . The actuators 10 can be attached directly to an element 3 , 4 or to a support structure 1 of the object 2 . The configurations of the method 200 described above can be converted accordingly.

2 shows a second embodiment variant of a device 101 according to the invention for carrying out the method 200. The device 101 is suitable for removing support structures 1 from an object 2 (in particular with particularly filigree target structures) which is immersed in a liquid. For this purpose, the device 101 has a base plate 7 on which the object 2 is provided in a positioning area 8 . In an edge region 9 of the base plate 7 , actuators 10 , in particular piezoelectric actuators 11 , are in turn arranged along one side of the base plate 7 .

The actuators 10 or piezoelectric actuators 11 are in turn connected to a controller 18 via lines 17, but this is not shown in FIG. 2 for the sake of simplicity. For the configuration of the controller 18, reference is made to the above description of FIG.

The device 101 also has vessel walls that hold the liquid within the device 101, which is not shown in detail in the figures. The device 101 is evacuated to a pressure slightly above the vapor pressure of the liquid to be used and then filled with the liquid covering the object 2 . Thereafter, the device 101 is vented again, filling the cavities of the object 2 with the liquid and avoiding the entrapment of air bubbles.

In a further embodiment variant, the liquid can also not completely cover the object 2 . The support structures to be removed can preferably also protrude from the liquid in order to keep the quality of the resonance vibrations of the vibration system high. A plane wave (with infinite focus length) is then sent in one direction by means of suitable control of all piezo actuators 11, and after the wave has been emitted, the piezo actuators 11 are switched as sensors. The resonance response to the plane wave excitation is recorded by the sensors. A large number of waves can then be emitted in further directions and the steps described above can be repeated with different focal lengths, if necessary. A sonographic image of the support structures 1 in the object 2 can thus be obtained. Furthermore (in the course of this or in a separate step) the vibration quality of the support structures 1 can also be determined.

As already described for FIG. 1 , the support structures 1 can be removed according to a method 200 .

In the case of the device 101, in which the support structures 1 are immersed in a liquid, the support structures 1 are preferably designed to be as fine or filigree as possible, as permitted by the manufacturing process. In this way, despite the reduced quality of the resonant vibrations, the connections 5 can be easily released.

3a, 3b and 4-7 show schematic cross-sectional views of vibration systems 6, 6.1-6.7 with different support structures 1, 1.1-1.13 according to different embodiment variants.

The support structures 1, 1.1-1.13 can be adapted or manufactured as part of a method 300 for the production of an object 2 in such a way that their resonance frequency in relation to the vibration system 6 is lower than the resonance frequencies of resonance vibrations in relation to the first or second element 3, 4.

3a shows a vibration system 6 with a support structure 1 according to a first embodiment. The support structure 1 includes only one predetermined breaking point

21 provided between the connections 5 to the first and second elements 3,4.

3b shows a vibration system 6.1 with a support structure 1.1 according to a second embodiment variant. The support structure 1.1 contains two constrictions

22, which represent flexure joints and/or predetermined breaking points 21, and between them a leg 23 which enables the resonance movement and deflection of the support structure 1.1 between the predetermined structures 3, 4, which can lead to the connections 5 being loosened.

Both support structures 1 and 1.1 are designed to be rotationally symmetrical about the z-axis. At the constrictions 22, the leg 23 can thus be rotated along an axis of rotation 24 in the z-direction and linearly deflected along the horizontal axes (x, y). With multiple arrangement of the support structures 1 or 1.1 next to each other (e.g. to support an extensive area), the use of the support structure 1 (according to FIG. 3a) leads to a relatively stiff connection, while the use of the support structure 1.1 (according to FIG. 3b) leads to a mobility in the horizontal plane. In this way, excitation energy can be collected in the entire vibration system 6.1 over several vibrations, with the collected energy leading to a high deflection and thus to the breakage or loosening of the connections 5 and thus to the release of the target structures 3, 4. The design of the support structure 1.1 can thus contribute to easier, reliable removal of the same.

According to FIG. 4a, a vibration system 6.2 with a support structure 1.2 according to a third embodiment variant is shown, and according to FIG. 4b, a vibration system 6.3 with a support structure 1.3 according to a fourth embodiment variant.

The support structures 1.2, 1.3 shown are designed as plates that extend along the y-direction. The support structures 1.2, 1.3 have constrictions 22 in their connection 5 to the first element 3, which are designed as grooves running along the y-axis on both sides of the support structures 1.2, 1.3.

The support structure 1.2 in FIG. 4a has a wider flexure joint at its upper connection 5 to the second element 4, which is also formed by a groove-shaped constriction 22 running along the y-axis. In this case, the vibration system 6.2 can only be excited along the x-axis and enable a resonant deflection of the leg 23. Due to the high mass of the support structure 1.2 and the relatively stiff connection 5 to the second element 4, the resonant frequency in the vibration system 6.2 is significantly reduced.

The support structure 1.3 in FIG. 4b has an alternative predetermined breaking point 21 at its upper connection 5 to the second element 4. FIG. The predetermined breaking point 21 is formed by three constrictions 22 arranged one behind the other in the x-direction, which in turn extend in the form of a groove along the y-axis. The central constriction 22 is located inside the connection 5 or the flexure joint. As a result, a deflection of the leg 23 in the x-direction induces a rotation about the y-axis, which exerts a very large compressive or tensile force on the predetermined breaking point 21 and thus makes it considerably easier to loosen the connection 5 .

A support structure 1.3 as shown in FIG. 4b is particularly suitable when using building material with very high toughness, where a constriction 22 corresponding to the support structure 1.2 cannot exert sufficient deflection or force to exceed the breaking point of the connection 5. Through the inner constriction 22 in the support structure 1.3, the pivot points along the y-direction and along the z-direction from the center of Leg 23 are moved out and so the lever acting on the predetermined breaking point 21 can be increased.

According to FIG. 5a, a vibration system 6.4 with a support structure 1.4 according to a fifth embodiment variant is shown, and according to FIG. 5b, a vibration system 6.5 with a support structure 1.5 according to a sixth embodiment variant is shown.

The support structure 1.4 in FIG. 5a is basically based on the design of the support structure 1.1 shown in FIG. 3b. For a general description, reference is therefore made to the above description of FIG. 3b. However, the diameter of the leg 23 is significantly widened, which increases the mass of the support structure 1.4 and the moment of inertia of the leg 23 about the z-axis. Due to the increased mass, the resonant frequency in the vibration system 6.4 is lowered on the one hand and on the other hand the vibration system 6.4 can easily collect and store vibration energy due to the high inertia. In this way, the support structure 1.4 can be broken off when its resonant vibration is excited, even if the amplitude of the excitation vibration is low. In alternative variants, the leg 23 can also have a square, triangular, hexagonal or other cross section.

The support structure 1.5 shown in FIG. 5b is in turn designed similarly to the previously described support structure 1.4, although this is deliberately designed asymmetrically. This allows linear excitation vibrations to be converted into rotational vibrations (and vice versa if necessary). This is advantageous in many areas of application of the invention, since linear excitation oscillations can often be produced more easily by a device 100, 101 using the actuators 10.

In addition, in the case of linear excitations, the sum of all accelerations at each point of the object 2 is (approximately) constant, while the acceleration in the case of rotational movements depends on the distance to the point of rotation or to the axis of rotation, which can lead to unwanted acceleration-related damage to target structures at exposed points . A more reliable method 200 or 300 can be created by using linear excitations.

FIG. 6 shows a vibration system 6.6 with two support structures 1.6 according to a seventh embodiment variant of the invention. The support structures 1.6 are designed to be essentially comparable to the support structure 1.5 shown in FIG. 5b, which is why reference is made to the general description in this regard. In contrast to the support structure 1.5, the legs 23 have cantilevers 25 along the x-direction in order to obtain an asymmetrical shape of the leg 23. Through the cantilever 25, a lever is generated which at linear Excitation in the y-direction couples a strong rotational vibration of the support structures 1.6 along the axis of rotation 24 in the z-direction into the vibration system 6.6.

Due to the rotational oscillation (torsional pendulum movement), the constrictions 22 on the connections 5 are subject to a high load, which can quickly lead to the connections 5 being torn off and loosened. The vibration system 6.6 has at least two vibration modes for the respective rotation of the support structures 1.6. With simultaneous excitation of the resonant vibrations of both vibration modes by one or more excitation vibrations, a substantially simultaneous removal of the support structures

1.6 take place.

7 shows a vibration system 6.7 consisting of several support structures 1.7-1.13. The configuration of the support structures 1.7-1.13 is based on the support structures 1.2, 1.3 shown in FIGS. 4a and 4b, which extend linearly (plate-like) along the y-direction. For a general description of the support structures 1.7-1.13, reference is made to the description of FIGS. 4a and 4b for the support structures 1.2, 1.3.

The support structure 1.7 has two legs 23 which are separated by a linear groove-shaped constriction 22. In the case of linear excitation in the x-direction, the legs 23 can be deflected into a rotational vibration relative to one another with a rotational axis along the y-direction.

The support structure 1.8, on the other hand, has three legs 23 arranged next to one another, which in turn are each separated by groove-shaped constrictions 22 along the y-axis. The support structure 1.8 can be excited at a higher resonant frequency than the support structure 1.7. The support structure 1.8 generates at least two vibration modes, one of which corresponds to a mutually opposite rotation of the legs 23 about the y-axis and the other corresponds to a uniform linear vibration of all three legs along the x-axis.

The support structure 1.9 in turn represents a continuation of the principle from the support structures

1.7 and 1.8 and has four legs 23 connected to one another by constrictions 22 . In this case, in turn, a plurality of vibration modes can be generated, with the resonant frequency being able to be further increased.

This principle is particularly beneficial when removing concrete support structures. Here, when breaking off, the support structures can be broken into small manageable blocks which can be easily removed and reused or disposed of. The support structure 1.10 differs from the support structure 1.7 in particular in that the constriction 22 at the upper connection 5 to the second element 4 differs from the other constrictions 22. The angle of the notch, which defines the constriction 22 and thus the predetermined breaking point 21, is more acute, which promotes the tearing and loosening of the connection 5 at this point.

The design of the support structure 1.11 is strongly based on the support structure 1.3 shown in FIG. 4b. The support structure 1.11 has an inner constriction 22 in the upper connection 5 to the second element 4, which enables a particularly favorable and simplified tearing behavior at the predetermined breaking point 21 through a linear excitation vibration along the x-axis.

The design of the support structure 1.12 combines the features of the support structures 1.11 and 1.6 from FIG. This creates a mechanical resonator with particularly favorable entry properties at the predetermined breaking point, which can be excited by linear excitation along the y-axis (or along the z-axis) in addition to the rotational vibrations that can be excited about the z-axis. These vibrations tend to first tear the predetermined breaking point 21 at an extreme point, i.e. at the beginning or at the end of the support structure 1.12 (along the y-axis), which further promotes the release of the connection 5 and thus enables an even gentler process.

Finally, the support structure 1.13 is based on the support structure 1.12, with the arms 25 of the legs 23 being provided on both sides of the legs 23. The moment of inertia of the legs 23 is further increased both about the z-axis and about the y-axis. In this way, the connection 5 can be released at the predetermined breaking point 21 according to the invention even more gently (with lower excitation amplitudes). However, this requires an excitation in the x-direction and along the z-axis.

Claims

patent claims

1. A method for removing support structures (1, 1.1-1.13) from an object (2), which was produced by an additive manufacturing process and in which at least one support structure (1, 1.1-1.13) between a first element (3) and a second element (4) of the object (4) is provided and in each case has at least one connection (5) thereto and in which the support structure (1, 1.1-1.13) together with the first and second element (3, 4) has a vibration system ( 6, 6.1-6.7), at least one of the connections (5) being released by stimulating the vibration system (6, 6.1-6.7) by means of mechanical vibrations, wherein by means of at least one actuator which is coupled to the object (2), at least a mechanical excitation vibration is introduced into it and fed to the vibration system (6, 6.1-6.7), and that

Vibration system (6, 6.1-6.7) is excited with at least one resonance vibration assigned to it in order to release the at least one connection (5), the deflection of the resonance vibration exceeding the load limit at at least one point in the vibration system (6, 6.1- 6.7), characterized in that the first element (3) is a target structure or an intermediate plate and the second element (4) of the object (2) is a base plate (7) of the object (2) and the at least one actuator (10 ) is coupled to the first element (3).

2. The method according to claim 1, characterized in that the resonance vibration associated with the vibration system (6, 6.1-6.7) corresponds to the excitation of at least one natural mode of the vibration system (6, 6.1-6.7).

3. The method according to claim 2, characterized in that the at least one natural mode of the vibration system (6, 6.1-6.7) is a deformation vibration of the support structure (1, 1.1-1.13).

4. The method according to any one of claims 1 to 3, characterized in that a single actuator (10) is coupled to the first element (3) and introduces a mechanical excitation vibration into the first element (3), with which it drives the first element ( 3) put into resonance vibration, whereupon the actuator (10) changes the excitation vibration to a counter-vibration and thereby supports the breaking off of the support structure (1, 1.1-1.13).

5. The method according to any one of claims 1 to 3, characterized in that several actuators (10) coupled to the first element (3) and optionally the second element (4). and introduce several mechanical excitation oscillations, the excitation oscillations in the oscillation system being superimposed to form the resonance oscillation.

6. The method according to claim 5, characterized in that at least one actuator (10) is attached to a support structure (1, 1.1-1.13) of the object (2).

7. The method according to any one of claims 1 to 3, characterized in that at least one actuator (10) on the base plate (7) of the object (2) is attached and the actuators (10) on the first element (3) and are attached to the base plate (7), which have the same or a similar excitation frequency, with similar excitation frequencies differing from one another by a maximum of 10% based on the lower excitation frequency.

8. The method according to any one of claims 1 to 7, characterized in that, in addition to the excitation of the vibration system (6, 6.1-6.7) with the at least one

Resonant vibration, a mechanical impulse in the base plate (7) or the support structure (1, 1.1-1.13) is initiated.

9. The method according to any one of claims 1 to 8, characterized in that the object (2) is freely suspended or freely suspended during the method (200).

10. The method according to any one of claims 1 to 9, characterized in that the resonance frequency of the resonance vibration is determined and the excitation frequency of the excitation vibration depending on the resonance frequency, in particular in a control device (20), particularly preferably in a control loop, is adjusted.

11. The method as claimed in one of claims 1 to 10, characterized in that the at least one excitation oscillation has a pulsed sinusoidal oscillation and/or a band noise and/or a frequency sweep.

12. A device for removing support structures (1, 1.1-1.13) from an object (2), the object (2) being an object (2) produced by an additive manufacturing process and the object (2) having at least one support structure ( 1, 1.1-1.13) between a first element (3) and a second element (4) of the object (2), each having at least one connection (5) to the first element (3) and second element (4). and together with these forms a vibration system (6, 6.1-6.7), the device (100, 101) having at least one mechanical actuator (10) which is coupled to the object (2) for initiating a mechanical excitation vibration, and wherein the device (100, 101) has a controller (18) coupled to the at least one actuator (10), which is programmed to control the excitation vibration and the vibration system (6, 6.1-6.7) with at least one resonance vibration assigned to it to be stimulated in such a way that at least at one point in time the deflection of the resonant vibration exceeds the load limit at at least one point in the vibration system (6, 6.1-6.7), characterized in that the first element (3) is a target structure or an intermediate plate and the second element ( 4) the object (2) is a base plate (7) of the object (2) and that the device (100, 101) has a plurality of actuators (10) connected to the controller (18) and mechanically coupled to the object (2), wherein the controller (18) is programmed to initiate a plurality of excitation vibrations in the object (2), which are superimposed in the vibration system (6, 6.1-6.7) to form the resonance vibration, where at least one of the actuators (10) is coupled to the first element (3).

13. The device according to claim 12, characterized in that the controller (18) has a measuring device (19) for measuring the resonant frequency of the resonant vibration and a control device (20) for controlling the excitation frequency of the at least one excitation vibration, the measuring device (19) having is connected to the control device (20) and the control device (20) is set up to adapt the excitation frequency as a function of the resonance frequency.