DE102012011217A1 - Device, used to make three-dimensional hybrid component, comprises supporting unit, applying unit, and radiation unit, where plate-like body is disposed on upper side of support, is formed as contoured plug holder and comprises recesses - Google Patents

Abstract

The device comprises a supporting unit for supporting an object with a height adjustable support (5) during construction, an applying unit (3) for applying a construction material (1) to a building surface or a previously formed layer, and radiation unit for selectively radiating the layers of the building material to a cross-section of corresponding object points. A plate-like body (4) is disposed on an upper side of the support, is formed as a contoured plug holder for a prefabricated object base to be formed, and comprises recesses. The device comprises a supporting unit for supporting an object with a height adjustable support (5) during construction, an applying unit (3) for applying a construction material (1) to a building surface or a previously formed layer, and radiation unit for selectively radiating the layers of the building material to a cross-section of corresponding object points. A plate-like body (4) is disposed on an upper side of the support, is formed as a contoured plug holder for a prefabricated object base to be inserted, and comprises recesses whose shape and an outer contour correspond to the cross section of the object to be inserted into a prefabricated base and in which a prefabricated lower part of the object is fixed. The recesses are provided with different shapes and contours arranged for different prefabricated object parts, and are uniformly distributed over a surface of the plug holder. The fixing of lower part of the object in the plug holder is carried out by generating a negative pressure which pulls the pre-fabricated lower part into the recess of the plug socket in a direction of the support. An upper part of the object is solidified by radiation and successive solidification of layers of a powder of building material. The fixation between the prefabricated object base and the plug holder is carried out by a releasable adhesive bond and by clamping. The clamping between the recess and the prefabricated object base is carried out increasing temperature of the plug holder for extending the recess and by cooling of the plug holder with plugged object part. The plug holder is formed as an upper part of a two-element body, which is fixed to a lower part, which is detachably connected to the support of the device using a tension centering device. The lower part of the body is a plate-like part, and is also provided with recesses whose cross-section and shape correspond to the recesses in the upper part. The upper part and lower part are laterally clamped with one another in a parallel position, and the object bases pass through the recesses of the upper part and engage in recesses of the lower part. A fluid film is provided between the upper part and the lower part. The recesses are formed in a polygonal, a star, a triangular, an octahedral, a partially rounded, a sickle or a semi-circular shape. The device further comprises connecting elements, an electronic reading unit, and a sensor unit. The connecting elements are identical to plug holders, are configured for connecting the lower part or the support, and are differ in number and/or shape of the recesses. The electronic reading unit reads a data source arranged on the plug holder. The data source is used to identify the plug holder. The object base has a circumferential projection, which is mounted on the plug holder, and a predetermined breaking point. The sensor unit is configured for detecting a position of the object lower part, and is formed as a camera or an infrared sensor.

Description

The invention relates to a device for producing three-dimensional components, which consist of a prefabricated object base and a generatively constructed thereon shell after the construction process. Such components may be formed either as hybrid components, d. H. Components that permanently have a prefabricated object base, on which a generatively constructed object shell is arranged. However, it is also possible to separate the prefabricated lower parts connected after the construction process with the generatively constructed object upper part of the generatively constructed object upper parts, then the end product consists only of a generatively constructed section. Three-dimensional components according to the invention are therefore on the one hand the said hybrid components and on the other hand the generatively constructed components which are separated after the construction of a connected only during the construction phase with the upper part.

The tops of such components are prepared by successive solidification of layers of a particular powdered, radiation-settable building material, wherein a solidification takes place at the respective cross-section of the upper part corresponding locations. Known devices which are suitable for this purpose include a carrying device for carrying the object during the construction process with a height-adjustable support, furthermore a coating device is provided, which serves for the layered application of the building material on a building surface or an already previously formed layer. Furthermore, an irradiation device is provided for selectively irradiating the layers of the building material at the locations corresponding to the cross section of the object, usually a laser, the beam of which is directed via a controllable scanner onto the points to be solidified of the layer.

In such a device (eg according to DE 195 11 772 A1 ) is further arranged on the upper side of the support, a plate-like body which serves as a building board in the cited prior art, that is, on the upper side, the powdery building material of the first layer is melted.

The invention has the object of providing a device with the features of the preamble of claim 1 in such a way that it can be provided for the construction process in a simple way with parts on the generatively tops can be constructed, the lower parts in a simple and fast to be mounted on the carrier and the location of their use on the carrier is clearly predetermined. This object is solved by the characterizing features of claim 1. Advantageous developments emerge from the subclaims.

As the core of the invention it is considered to form the preferably plate-like body, which serves as a building board in the prior art, as a form-adapted plug-in support for at least one prefabricated lower part of an object to be built. In other words, this means that is usually not built on the plate-like body, but only on object bases, which are inserted into the serving as a holder body and exposed with a top to build. For this purpose, the body has at least one recess whose shape and outer contour corresponds to the cross-section of a prefabricated object lower part to be inserted into it and in which the inserted prefabricated object lower part can be fixed. The body will preferably be a plate-like body, its upwardly directed surface not necessarily being flat, because it is not usually built up thereon.

If, in this context, a fixation of the object lower parts in the plug-in holder is spoken of, then this is first understood to mean an exact positioning of the object lower parts in the section of the plug-in holder assigned to them, so that the respective object lower part in the X- and Y-direction, ie. H. is exactly positioned in the plate plane. Such an exact positioning - assuming a really good fit of the plug-in bracket - is usually sufficient to carry out a construction process. In most cases, forces that could be suitable for extracting such an inserted object base from the recess of the plug-in support during the construction process are not present or at least extremely slight.

A secure mounting of the inserted object bases also in the Z direction can be generated in different ways, eg. B: either by generating a negative pressure, which acts on the object bases from below and, as it were, draws into its recess and is fixed there. Also, the fixation between the prefabricated object base and the plug-in holder can be effected by a releasable clamping connection. A clamp connection can also be used to compensate for a certain amount of play in the X and Y directions, provided an exact fit between the contour of the object bases and the associated plug holder recess is eliminated for reasons of cost or installation. This would mean that the object base is then acted upon laterally within its associated recess and is pressed in the direction of one or more side walls of the associated recess.

Advantageously, a plurality of recesses with at least partially different shapes and contours are provided in a plate-like plug-in holder, in which different prefabricated object bases can be inserted. Advantageously, the plurality of recesses can be arranged distributed over the surface of the plug-in bracket for assembly or thermal reasons during the construction process substantially evenly.

It is also possible to support the fixation between the prefabricated object bases and the plug-in holder by means of a releasable adhesive bond, i. H. be avoided by a releasable adhesive that during the construction process, the inserted object bases in their associated recess of the plug-in holder work or can move upwards.

A realization of a clamping device may be to increase the temperature of the plug-in holder before inserting the object or the lower parts for temporary expansion of the recesses, then insert the object bases and then cool the plug-in holder again. This results within the recesses a very intimate clamping connection over several flanks or walls, so that the object bases are very precisely fixed. But it is also possible to form the plug-in holder as the upper part of a two-element body, which is attached to a lower part, which in turn with the carrier of the device z. B. is releasably connected by a clamping / centering device. This makes it possible to remove the two-element body, which is occupied by object bases, on which generatively upper parts are already constructed, by removing the chip / centering device from the device and inserting it into another device for post-processing the generatively constructed upper parts.

It when the lower part of the two-element and thus two-ply body is also plate-like and is also provided with recesses whose arrangement and shape corresponds to the recesses in the upper part is particularly advantageous. Then, namely, relatively long object bases can be used, which pass through the upper part of the two-layered body and protrude into the initially congruent arranged recesses of the lower parts. Then, if the plates are slightly displaced or braced against each other, then a fixation of a plurality of object bases in the plug-in holder can be carried out by such a bracing operation.

Advantageously, the recesses of different shape, for. B. polygonal as trapezoidal, triangular, star-shaped, octahedral or the like. And / or also partially rounded z. B. sickle-shaped or semi-circular or form a combination of polygons or partially circular formations. Object bases of appropriate shape can otherwise be "sorted" according to a key principle in the matching recesses of the plug-in bracket, which is particularly simple and fast.

In order to facilitate the coating process, provided as the basis for the generative structure surfaces of the prefabricated object bases are arranged substantially in the same plane as the top of the plug-in holder.

The invention is explained in more detail with reference to embodiments in the drawing figures. These show:

1 a schematic perspective view of the main components of a device according to the invention;

2 a modified device with a double-layer plug-in holder;

3 a schematic sectional view of a device with a double-layer plug-in holder;

4 a schematic sectional view of a device with another double-layered plug-in holder;

5 another embodiment of a double-layer plug-in holder with centering device;

6 an object base in a further embodiment;

7 an arrangement of several object subparts for joint processing and

8th further forms of object subdivisions, and

9 an embodiment of the plug-in holder with plug-in modules.

First, on drawing figure 1 Referenced. The device used in 1 is only partially shown, is used to produce three-dimensional objects by successive solidification of layers of a powdered building material 1 placed in a dosing tank 2 is stored and by an applicator 3 on a pad 4 can be piled up on a carrier 5 in a building chamber 6 attached and together with the carrier 5 in the construction chamber 6 is arranged adjustable in height. The applicator 3 is like one application blade 7 formed in the direction of the arrow 8th over the dosing chamber 2 can be moved while applying a thin layer of the building material on a corresponding surface. For solidification of this layer at the desired locations is an irradiation device 10 , In particular, a laser provided, a focused beam 11 the laser is going through a scanner device 12 directed to the areas of the building material layer corresponding to the cross section of the object to be built.

The preferably plate-like body 4 is as a form-fitting plug-in bracket 30 for at least one prefabricated object base 31 an object to be built up and has at least one recess for this purpose 32 on, the shape and outer contour of the cross section of a prefabricated object to be inserted into it 31 equivalent. In drawing figure 1 are two object sub-parts 31 represented in the form of a sickle and in the form of a trapezoidal body, in the corresponding recesses associated with them 32 can be used from above. The object sub-parts 31 are in the recesses 32 fixable, which can be done in different ways.

A first possibility of fixation is the fit between the recesses 32 and the contour of the object sub-parts 31 to provide so exactly that the object sub-parts 31 when inserting into the recesses 32 experience a quasi-sucking seat, so that they can not move in the plane of the plate nor there is a risk that they are in the process of editing up from their recesses 32 be pulled out.

But it is also possible, in other ways, a fixation of the object sub-parts 31 in your recesses 32 to make, for. B. by generating a negative pressure, the inserted prefabricated object base 31 into the recess 32 the plug-in bracket 30 in the direction of the carrier 5 pulls in and thus quasi fixed in the Z direction.

Another possibility would be a droplet of glue, with which the object base 31 in its recess 32 the plug-in bracket 30 can be fixed, the adhesive must be solvable, for example by heat or by an appropriate solvent.

Another possibility is between the plug-in bracket 30 and the object bases 31 to act a clamp what z. B. this can happen that the plug-in bracket before inserting the object bases 31 in the recesses 32 is heated, so that the recesses 32 slightly expand and then a cooling with inserted object bases 31 takes place, so that as a result of the contraction in the area of the recesses 32 the clamping is set. The plug holder 30 may be formed as the upper part of a two-membered or double-layered body, a lower part 33 This two-layered body can interact with the wearer 5 through a tensioning / centering device 40 be connected releasably and positionally accurate.

The lower part 33 of the body 4 can - like the top - be plate-like and also with recesses 32 ' be provided, their arrangement and shape with the recesses 32 in the upper part, ie in the plug holder 30 corresponds. Upper part and lower part 33 can be clamped in parallel position laterally to each other, thereby the prefabricated Untereile 31 that the recesses 32 of the upper part and in the recesses 32 ' of the lower part 33 In addition, engagement can be fixed both in the Z direction and in the XY direction (on the plate plane).

As in 1 and 2 represented are the recesses 32 . 32 ' polygonal, in particular star-shaped, triangular or octahedral, they may also be rounded in addition or separately in sections and be designed in the manner of a sickle or semicircular. Significant in this context is that the object bases can be easily plugged into an easy-to-overlook key / keyhole principle in their intended places of the plug-in bracket.

If the upwardly pointing surfaces provided for the generative construction of the object (s) of the inserted prefabricated object lower parts are arranged essentially in the same plane as the upper side of the plug-in holder, the coating process can be carried out in a simple manner and in a way that saves on building material.

The embodiment according to 2 is largely consistent with the example in 1 However, for reasons of clarity are the irradiation device, namely the laser 10 and the scanner 12 omitted. The embodiment according to 2 differs in that the plug-in bracket 30 on a lower part 33 is applied and there z. B. via a dowel pin 35 is pre-fixed. This allows the parts 30 and 33 be easily separated from each other. The recesses not occupied during the construction process 32 can with building material 1 filled, then due to the underlying plate, namely the lower part 33 not down to the carrier 5 fall through, so building material can be saved.

At the in 4 illustrated embodiment is the plug-in bracket 30 on the lower part 33 in turn pre-attached by a dowel pin and is in particular in the Z-direction by a magnet arrangement 45 fixed the plug holder 30 - provided this is made of a magnetizable material - against the lower part 33 pull and hold there. The same applies to magnetic object bases 31 ,

At the in 5 illustrated embodiment, the plug-in holder 30 on a lower part 33 be deferred, which does not necessarily have to be a flat plate, including a mutual dovetail guide 36 is provided, which is fixable by grub screws or the like. Transversely to the extension direction.

6 shows a further embodiment of a prefabricated object base 31 that has a circumferential lead 34 having. The circumferential projection 34 can either be one to the shape of the object base 31 However, it may also, for example, regardless of the shape of the object base 31 always have a circular or rectangular shape. By means of the circumferential projection 34 may be inaccuracies in the production of the recesses 32 be compensated. In particular, allows the circumferential projection 34 that the recesses 32 consistently allowed to get a little too big, so that no friction between the object base 31 and the plug-in bracket 30 takes place. The circumferential projection 34 then prevents too deep immersion of the object base 31 into the recess 32 ,

7 shows an arrangement of the object subparts 31 which allows a common processing. There are several object sub-parts for this purpose 31 in the plug-in holder 30 arranged. Between the plug holder 30 and the lower part 33 there is a liquid film 37 , The plug holder 30 and the lower part 33 can by means of one or more centering pins 38 be arranged accurately. As already to the object bases 31 and the recesses 32 can also run the centering pin 38 such on the recess of the lower part 33 be adjusted so that a frictional engagement takes place. The centering pins 38 but can also have a reduced compared to the recesses circumference, so that only a positioning of the plug holder 30 on the lower part 33 is possible, but no firm connection. Of course, the centering pins 38 also on the lower part 33 be attached, and the corresponding recesses are then on the plug holder 30 are located. Furthermore, it is also possible that a part of the centering pin on the lower part 33 and another part on the plug-in bracket 30 is arranged.

The joint editing of the object sub-parts 31 For example, by means of a grinding device 39 done in 7 is shown purely schematically. To differently shaped object bases 31 to make them accessible to the joint editing, these can be carried out in two parts, the first section 41 and the second section 42 of the object subpart 31 with a predetermined breaking point 43 are connected. On the right side of the plug-in bracket 30 is a one-piece standard object base 31 , at the height of which the adaptation of the two-part object sub-parts 31 with first section 41 and second section 42 he follows.

The provision of predetermined breaking points 43 is of course also possible if no joint processing of the object sub-parts 31 , for example by means of the grinding device 39 is provided. The division of object subparts 31 then allows the provision of standardized, ie identical recesses 32 , where the object sub-parts 31 so at least from the height of the standardized recesses 32 can be adjusted.

In a preferred embodiment, they become predetermined breaking points 43 directly above or below a circumferential projection 34 arranged. In this case, preferably, the second section 42 standardized or standardized recesses 32 adjusted so that the second section 42 , the breaking point 43 and the circumferential lead 34 form a kind of standard interface. The arrangement of the predetermined breaking point 43 is preferably above the circumferential projection 34 if the course of the breaking point 43 in particular not parallel to the surface of the plug-in holder 30 runs. Looking at the middle object bottom 31 in 7 , it is evident that in this embodiment, the predetermined breaking point of the circumferential projection 34 below the predetermined breaking point 43 must run, provided the circumferential projection 34 should not remain on the end object.

8th shows a further design possibility of the object sub-parts 31 , In this embodiment, the predetermined breaking points are 43 on second sections 42 such that they are after inserting the object sub-part 31 into the recess 32 just above the plug holder 30 are arranged. The second sections 42 can be standardized, but they do not have to. After the generative construction of the third section 44 on the first section 41 and removing the excess building material from the building chamber, the second sections 42 the object subparts 31 then simply by means of separation or cutting by means of a separator or by simply canceling at the predetermined breaking points 43 be separated.

The course of a construction process in a device according to the invention is summarized again below:
First, the plug-in bracket 30 to manufacture in which a preferably standardized plate with recesses 32 is provided. This is to be introduced into the building chamber.

For fixing the object bases 31 can the plug-in bracket 30 are heated, then the object bases 31 in the still heated plug-in bracket 30 introduced, with the object bases 31 automatically in the plug-in holder 30 to be trapped on cooling. In addition, of course, the other mechanisms already described above for clamping the object bases 31 possible.

After clamping, a joint revision of the surfaces of the object bases takes place 31 to an adjusted and exact height. This revision can be done by grinding or milling.

Then the plug-in bracket 30 with the clamped object bases 31 introduced into the device or the building chamber and fixed at the bottom of the building chamber by means of a Spannsystemsteckhalterung or by means of another fixing device in the building chamber. When inserting one on the plug holder 30 read by a chip attached security code, for which a corresponding read head is arranged at the bottom of the building chamber. By checking the security code can be determined whether the plug-in bracket 30 meets the intended requirements. The security code 30 can accordingly identify the plug-in bracket 30 or their properties. The security code can contain information about the number of recesses 32 , about its size, about the height of the plug-in bracket 30 or any other the plug-in bracket 30 deliver the relevant date so that a security clearance can take place.

Is the plug holder 30 suitable for the intended construction, the structure of the third section 44 on the first section 41 kick off.

After completion of the construction, the object sub-parts 31 at the predetermined breaking points 43 divided, so that the finished objects can be removed.

9 shows a further embodiment of the plug-in holder 30 , This is from plug-in modules 46 constructed, with at least one plug-in module 46 a recess 32 having. Not every plug-in module 46 must have such a recess, it can also plug-in modules 46 without recess 32 be provided, only for the stabilization and positioning of the remaining plug-in modules 46 serve. The plug-in modules 46 are doing in a kind of recording cup 47 used. Instead of the receiving tray 47 can the plug-in modules 46 but also on a lower part 33 be plugged, with each plug-in module 46 by means of a fixing device such as a dowel pin 35 in the lower part 33 to be stuck. This fixation may also be present in addition to providing a side wall.

In particular, in the embodiment with plug-in modules 46 it is advantageous, a sensor device for detecting the position of the recesses 32 or the object sub-parts 31 to be able to capture. With particular preference, the sensor device can detect not only the position but also the orientation of non-rotationally symmetrical object bases. Thereby, a faulty solidification of the building material can be avoided. In particular, it becomes possible either the construction process to the position and orientation of the plug-in modules 46 adapt or beyond also possible to detect if the recesses 32 the plug-in modules 46 have the right shape. This is of course not on the design of the plug-in bracket 30 as plug-in modules 46 limited, this review by means of sensor device can of course in each embodiment of the plug-in bracket 30 respectively. With respect to the center of the plug holder 30 Centrally symmetrical alignment of the recesses 32 These are independent of the rotation of the plug holder 30 always in the same position, only the shape of the recesses 32 is still to be checked.

The sensor device can be designed as a camera. This is after checking the plug-in bracket 30 at least from the area of the process chamber, as the temperatures prevailing during the construction of the object would damage the camera. Alternatively, other measuring devices can be used, which are adapted to the position and / or the shape of a recess 32 capture.

LIST OF REFERENCE NUMBERS

1

construction material

2

dosing

3

applicator

4

body

5

carrier

6

Construction Chamber

7

application blade

8th

arrow

10

irradiation device

11

beam

12

scanner device

30

plug socket

31

Object base

32

recess

33

lower part

34

circumferential lead

35

Passstifft

36

dovetail guide

37

liquid film

38

spigot

39

grinding device

40

Clamping / centering

41

first section

42

second part

43

Breaking point

44

third section

45

magnet assembly

46

plug-in module

47

receiving dish

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19511772 A1 [0003]

Claims (18)

Device for producing three-dimensional components which, after the construction process, consist of a prefabricated lower part and an object upper part generatively constructed thereon, wherein the upper part of the object is formed by successive solidification of layers of a particular pulverulent, radiation-hardenable structural material ( 1 ) is carried out at the locations corresponding to the respective cross section of the object upper part, and the device comprises: a carrying device for carrying the object during the construction process with a height-adjustable support ( 5 ), - an application device ( 3 ) for the layered application of the building material ( 1 ) on a building surface or an already formed layer and - an irradiation device ( 10 ) for the targeted irradiation of the layers of the building material ( 1 ) at the locations corresponding to the cross section of the object, wherein - on an upper side of the support ( 5 ) at least one preferably plate-like body ( 4 ), characterized in that - the preferably plate-like body ( 4 ) as a form-fitting plug-in holder ( 30 ) for at least one prefabricated object base ( 31 ) of an object to be built up and - at least one recess ( 32 ), whose shape and outer contour correspond to the cross-section of a prefabricated object lower part ( 31 ) and - in which the inserted prefabricated object base is fixable. Apparatus according to claim 1, characterized in that in the plate-like plug holder ( 30 ) several recesses ( 32 ) with at least partially different shapes and contours for the use of different prefabricated object sub-parts ( 31 ) are arranged. Apparatus according to claim 1 or 2, characterized in that the plurality of recesses ( 32 ) over the surface of the plug-in holder ( 30 ) are distributed substantially evenly. Device according to one of the preceding claims, characterized in that the fixing of at least one inserted prefabricated object base ( 31 ) in the plug-in bracket ( 30 ) by generating a negative pressure that the inserted prefabricated object base ( 31 ) in the recess ( 32 ) of the plug-in bracket in the direction of the carrier ( 5 ) and fixed in it. Device according to one of the preceding claims, characterized in that the fixation between the prefabricated object base ( 31 ) and the plug-in bracket ( 30 ) by a releasable adhesive bond. Device according to one of the preceding claims, characterized in that the fixation between the prefabricated object base ( 31 ) and the plug-in bracket ( 30 ) by clamping, including the temperature of the plug-in bracket ( 30 ) before inserting the at least one prefabricated object sub-part ( 31 ) for the temporary extension of the at least one recess ( 32 ) is increased and by cooling the plug-in bracket ( 30 ) with inserted object lower part ( 31 ) the clamping connection between the at least one recess ( 32 ) and the prefabricated object base (s) inserted into it ( 31 ) he follows. Device according to one of the preceding claims, characterized in that the plug holder ( 30 ) as the upper part of a two-element body ( 4 ) is formed on a lower part ( 33 ), which is connected to the carrier ( 5 ) of the device by a clamping / centering device ( 40 ) is releasably connected. Device according to claim 7, characterized in that the lower part ( 33 ) of the body ( 4 ) is plate-like and also with recesses ( 32 ' ) whose arrangement and shape with the recesses ( 32 ) corresponds in the upper part. Device according to claims 7 or 8, characterized in that the upper part and the lower part ( 33 ) are clamped laterally in parallel position to each other and the prefabricated object bases ( 31 ) the recesses ( 32 ) of the upper part and in recesses ( 32 ' ) of the lower part ( 33 ) intervene. Device according to claims 7 to 9, characterized in that between the upper part and the lower part ( 33 ) a fluid film is provided. Device according to one of the preceding claims, characterized in that the recesses ( 32 . 32 ' ) are polygonal, in particular star-shaped, triangular or octahedral and / or rounded in sections, in particular crescent-shaped or semicircular. Device according to one of the preceding claims, characterized in that the upwardly pointing, provided for the generative structure of the object or the object tops surfaces of the prefabricated object bases ( 31 ) substantially in the same plane as the top of the plug-in bracket ( 30 ) are arranged. Device according to one of the preceding claims, characterized in that it comprises a plurality of plug-in holders ( 30 ), in particular identical connection elements for connection to the lower part ( 33 ) or the carrier ( 5 ), and only in the number and / or the shape of the recesses ( 32 ). Device according to one of the preceding claims, characterized in that it comprises an electronic reading unit, one at the plug holder ( 30 ) read data source, wherein the data source for identifying the plug holder ( 30 ) serves. Device according to one of the preceding claims, characterized in that the at least one prefabricated object lower part ( 31 ) has a circumferential projection, with which it on the plug holder ( 30 ) is storable. Device according to one of the preceding claims, characterized in that the at least one prefabricated object lower part ( 31 ) has a predetermined breaking point. Device according to one of the preceding claims, characterized in that it comprises at least one sensor device for detecting the position of the at least one prefabricated object lower part ( 31 ) having. Apparatus according to claim 17, characterized in that the sensor device is designed as a camera or infrared sensor.

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