DE102015205188A1 - Creating a three-dimensional structure - Google Patents

Abstract

The 3D printing should be made more variable. For this purpose, a method and an apparatus for producing a three-dimensional structure are proposed. In this case, a base body (1, 3) is provided with a first surface section (6) having a first surface normal and a second surface section (7) whose second surface normal is not parallel to the first surface normal. On the first surface section (6), in each case perpendicular to the first surface normal, a plurality of layers (8, 9) are respectively applied vertically. Likewise, a plurality of layers (8, 9) are applied to the second surface portion (7) perpendicular to the second surface normal by the 3D printing method. Thus, an additive application takes place in several spatial directions.

Description

The present invention relates to a method for producing a three-dimensional structure by providing a base body having a first surface portion having a first surface normal and a second surface portion whose surface normal is not parallel to the first surface normal, and applying a plurality of layers to the first surface portion, respectively perpendicular to the first surface normal through a 3D printing process. Moreover, the present invention relates to a corresponding device for producing a three-dimensional structure.

More and more three-dimensional structures and bodies are produced today by 3D printing processes. The materials used are different. In many cases plastic is used. Polymers, for example, can be applied liquid in layers and hardened. Alternatively, polymers can also be processed by selective laser sintering. Other materials such as ceramics and metals can also be applied in layers by selective laser melting or electron beam melting. Such 3D printing methods are also known as stereolithography.

In 3D printing, a first layer is usually applied and cured on a printing platform. In the same way, a second layer is applied, etc. By displacing the edges of the different layers different geometries and structures can be achieved.

However, the planar layered application limits 3D printing to certain shapes of the structures to be printed. For example, the object should always have a defined footprint. Cavities can be made very complex with filler, which carries a newly applied layer of 3D printing. For example, a structure with a built-in object made of a different material can only be fabricated if the object does not interfere with the printhead when the layers are applied.

Special problems exist in the production of gradient coils for MRI devices (magnetic resonance tomography). Such coils have many individual parts, which are typically assembled by hand. The high forces that occur in the operation of such a gradient coil, often cause that relaxes one or the other part. Accordingly, great care must be taken so that the items are mounted without play. Typically, therefore, the components of gradient coils, such as sensors, cooling elements and interfaces, are molded together with the actual coils. Especially at the interfaces, e.g. Cooling, the gradient coils X, Y and Z, the sensors and the mechanical recordings, namely otherwise occur more damage.

The defective components can usually be replaced only on site with great effort. Repairs are usually limited.

The object of the present invention is therefore to provide a method and a device with which even more complex three-dimensional structures can be produced more easily.

• – Bereitstellen eines Grundkörpers mit einem ersten Oberflächenabschnitt, der eine erste Oberflächennormale besitzt, und einem zweiten Oberflächenabschnitt, dessen zweite Oberflächennormale nicht parallel zu der ersten Oberflächennormale ist,
• – Auftragen mehrerer Schichten auf den ersten Oberflächenabschnitt jeweils senkrecht zu der ersten Oberflächennormale durch ein 3D-Druckverfahren, sowie
• – Auftragen mehrerer Schichten auf den zweiten Oberflächenabschnitt jeweils senkrecht zu der zweiten Oberflächennormale durch das 3D-Druckverfahren.

According to the invention, this object is achieved by a method for producing a three-dimensional structure

• Providing a base body having a first surface portion having a first surface normal and a second surface portion having a second surface normal not parallel to the first surface normal,
• - Applying multiple layers on the first surface portion respectively perpendicular to the first surface normal by a 3D printing process, as well
• - Applying multiple layers on the second surface portion respectively perpendicular to the second surface normal by the 3D printing process.

Advantageously, in the 3D printing process, the layers are therefore no longer applied all perpendicular to a single normal. Rather, layers are also applied perpendicular to at least a second normal, which is not parallel to the first surface normal. This means, for example, that additive coatings can be applied to a body from several sides. In particular, for example, correspondingly curved layers can also be applied to a curved surface. For the specific example of a gradient coil in the MRT method, components can be additively applied or printed onto a drum, for example, whereby the drum can rotate around its axis of rotation.

The main body can be, for example, a printing platform which is not part of the three-dimensional structure actually to be printed and is removed after printing. The basic body can also be a carrier, which remains part of the three-dimensional structure. In particular, the base body may already be a printed structure which is further printed.

A special embodiment of the method may consist in that during the application of the layers, a shell-shaped structure is formed, in the cup-shaped structure a flowable filler material is introduced, in the filling material, an object is pressed or sunk that it relative to the cup-shaped structure a predetermined Position reached, the filling material is such that it holds the object in the predetermined position at least partially, and then further layers are applied to the cup-shaped structure and the object by the 3D printing process. It is therefore first formed by the 3D printing process, a kind of shell into which the flowable filler material is filled. It must therefore be flowable, so that it can be displaced by an object, which is introduced into the shell or in the shell-like structure. The filler may be liquid, viscous or waxy. Alternatively, it can also be a sand. In addition, the filler may be a mixture of the above materials. The filling material can fulfill one or more tasks. On the one hand, it can be a carrier for further layers to be printed on. In addition, it may serve to partially hold the object to be imprinted into the structure by the 3D printing process. But it can also be so viscous that it completely carries the object and holds it in place. The material properties of filling material and object are preferably matched to one another. In this position held by the filling material, the object can be printed again by the 3D printing process.

According to an alternative embodiment, the base body is produced by printing a shell-shaped or shaft-shaped structure by means of the 3D printing process, in which an object is inserted in a form-fitting manner. This variant has the advantage that no filler material must be used and compliance with the position of the object is ensured by the fact that a positive connection is made. The shaft-like structure can also be open to several sides. Held by the shell or the shaft, the object can then be printed from several sides.

According to a further embodiment, an object is held on the applied layers by a robot in a predetermined position, and subsequently further layers are applied by the 3D printing method to the already applied layers and the object in the predetermined position. This provides a highly flexible way to print objects into almost any position in a structure. In this case, the object first held is for example printed so long, i. surrounded by material until it is held in the desired position by the material. Subsequently, the robot arm can release the object and if necessary, then the remaining object can be printed.

In addition, the object can be completely or partially enclosed by layers applied by the 3D printing process. For example, objects that communicate wirelessly with the environment can be completely enclosed by the printed layers. In turn, other objects that need external interfaces, such as coils, cooling elements, or mechanical supports, can be surrounded as much as possible with the 3D printing process without affecting their interface functionality.

If a filling material is used in the 3D printing, it is favorable if, after the object has been pressed into the filling material, excess filling material is drawn off or sucked off by a suction robot. In this way, the surface of the filling material can be given a defined shape.

The multiple layers applied in the 3D printing process may consist of at least two different materials, with each material being applied separately from a respective robotic arm. Each robot arm performs a 3D print with a special material. In this way, the printed three-dimensional structure may consist of different materials. If necessary, the individual robot arms also work simultaneously, so that the multi-material structure can be built up very quickly.

The 3D printing process may include spraying, sintering or welding, but also gluing or UV-polymerizing. All of these additive techniques are suitable for applying material three-dimensionally in many layers one above the other.

According to a specific embodiment, the main body can be rotated in the 3D printing process. By turning the body can be printed on several sides of this body material. This rotation of the body is often cheaper than turning the printhead against the body.

In particular, the rotation of the body is then when this is cylindrical and is rotated about its longitudinal axis. Thus, this method can for example be used particularly advantageously for the coil system of an MRI apparatus. As a result, the individual coils, the cooling, the sensors and mechanical recordings can be attached to a cylindrical carrier body imprint or embed by pressure on the surface.

According to the invention, an apparatus for producing a three-dimensional structure is also provided. This device has means with which the above-described method steps can be performed. In particular, it has a printhead for the 3D printing process. This printhead is displaceable relative to the main body or its holder in at least three directions or rotatable about a plurality of axes. In this way, it is possible that the print head on two mutually inclined planes in each case several layers one above the other.

Preferably, the apparatus has a five-axis printhead for the 3D printing process so that the printhead can print an object or a base from multiple sides.

In addition, the apparatus for manufacturing the three-dimensional structure may further include a multi-axis robot that operates independently of the printhead and that is configured to hold an object in a predetermined position so that it can also be printed. This is a very flexible device given that can be imprinted in a three-dimensional structure in almost any predetermined positions objects.

The means and in particular the print head or its control are in particular also able to carry out the functions mentioned above in connection with the described method individually or in combination.

The present invention will now be explained in more detail with reference to the accompanying drawings, in which:

1 a schematic diagram of a first embodiment of the present invention with a form-fitting introduced object;

2 a second embodiment in which an object is held by a robot hand;

3 a third embodiment in which an object is held by a filling material;

4 an arrangement for a 3D printing with suction robot;

5 the printing of a structure on a curved base body; and

6 a schematic diagram of a 3D printer and a holding robot when printing.

The embodiments described in more detail below represent preferred embodiments of the present invention. It should be noted that the individual features can be used not only in the described combinations, but also in isolation or in other technically meaningful combinations.

By a 3D printing method, a three-dimensional structure is produced, for example, by spraying, gluing, UV-polymerizing, sintering, welding or the like. For example, an object is imprinted in the structure. The starting point for 3D printing is a basic body, which is ultimately part of the three-dimensional structure or which is the carrier of the three-dimensional structure to be produced only during the printing process.

In the example of 1 was initially a structure 1 printed, which is a manhole 2 having a predetermined dimension. The shaft 2 can only be open upwards or after several pages. The internal dimensions of the shaft 2 are predetermined in such a way that they contain an object 3 can be introduced positively. This object 3 will now of the structure 1 kept in position during the course of the 3D printing process.

The structure 1 is on the object to be applied or used 3 in terms of shape so tuned that it is the object 3 holds positively in the assembled state. As a result, it can no longer change position during further printing. Such a positive connection, for example, also arise because the structure 1 and the object 3 have at least one spring and a groove.

In 1 is still a printhead 4 indicated for the 3D printing process. This can preferably be moved in all spatial directions, which indicates the arrow cross. In addition, it may optionally be provided that the print head 4 is rotatably mounted about one or more axes (see. 6 ).

At the object 3 it can be any body to be imprinted into the three-dimensional structure. For example, it is a mechanical component such as a bearing element or an electrical component such as a coil. The object 3 however, is not limited to the examples given. In particular, the object may not even exist and a printed structure serves as a base for further printing.

The printed entity 1 together with the inserted or attached object 3 now forms the main body for the further 3D printing process. This main body has a plurality of surface portions that are not parallel to each other. Each of these surface sections has a corresponding surface normal. For example, the main body has here on the object 3 a surface section 6 with a first surface normal. In addition, the main body has on the structure 1 a second surface portion 7 with a corresponding second surface normal. The first surface section 6 is not parallel to the second surface section 7 , The spatially movable printhead 4 can now access the surface sections 6 and 7 , which are aligned differently, in each case a first layer 8th apply what is in 1 on the opposite side of the printhead 4 is shown on the base body. In the course of further 3D printing, the printhead carries 4 a second layer 9 on. This second layer 9 lies in a partial area not only in the direction of the first surface normal with respect to the first surface section 6 over the first layer 8th but in another part of the area also in the direction of the second surface normal with respect to the second surface portion 7 over the first layer 8th , Due to its spatial mobility is the printhead 4 So able to apply layers in several spatial directions additively one above the other.

The advantage of such a movable printhead 4 But especially comes into play when the object 3 has an undercut with respect to the vertical direction, which can not be filled with material from above by a conventional printing process. But also in the example of 1 it can be seen that with a conventional printhead no longer on the surface section 7 could be imprinted when the object 3 into the structure 1 is used. This is because the printhead 4 has larger dimensions than the width of this second surface section 7 so the tip of the printhead 4 the second surface section 7 from above can not reach. A usual, purely vertically oriented printing process would not be suitable, the object 3 as in the example of 1 into the structure 1 to imprint.

In 2 another embodiment of the present invention is shown. There is a robotic arm 10 the object 3 on the structure 1 , The structure 1 here in its shape does not have to match the shape of the object 3 be aligned. The main body for the 3D printing process consists here of the loosely related parts 1 and 3 , But here, too, the base body has at least two differently oriented surface sections 6 and 7 , In the further printing process, for example, starting on the surface portion 7 a layer 11 after the other to the object 3 applied until the layers 11 also on the surface section 6 of the structure 3 be applied. This is only possible because here the printhead (in 2 not shown) also the object 3 can drive around in space. Finally, a three-dimensional structure emerges, in which the object 3 in that with the layers 11 supplemented structures 1 is imprinted or integrated.

In this way, for example, the impression of support elements, flanges, plug contacts, etc. by means of a separate robot arm 10 in the 3D printing process, for example, for a gradient coil of an MRI device possible. The supporting robot holds this element in position and the 3D printer prints the structure around the element. The input variable is preferably a CAD model. Where appropriate, the different materials are also clearly defined or assigned. Advantageously, bionic design is used, ie the surfaces are rounded according to the principle of uniform constant surface tension, which is readily feasible with the spatially movable print head.

Another embodiment is in 3 shown schematically. This is in a bowl-shaped structure 1 a filler 12 filled. This filling material 12 can be liquid, viscous or waxy. Optionally, the filler material 12 also a sand. It is only important that the filling material 12 is flowable, hence the object 3 can be pressed or sunk into the filler. The material properties of the filling material 12 Like viscosity and density can be so on the object 3 be agreed that the object 3 alone through the filler 12 can be held. Alternatively, the object may be 3 also on the walls or edges of the structure 1 support when the filler material 12 the object 3 not alone.

The filling material 12 has the (additional) task to wear layers that are applied by the 3D printing process. In the present example of 3 Can be used with the movable printhead (in 3 also not shown), for example, a layer 13 are applied first by the edge of the structure 1 over the filling material 12 to the object 3 and printed across it. On this layer 13 Now again a new layer can be printed.

Upon completion of the 3D printing process, the filler becomes 12 if necessary removed.

In 4 is another example similar to that of 3 shown. The structure 1 here again has a bowl-shaped recess in the filler 12 is filled. The object 3 is in the filler 12 pressed. The mass of the object 3 leads to a level increase of the filling material 12 , This level rise is here by a vacuum robot 14 balanced. This sucks after pushing the object 3 an analogous amount of filler material 12 from. Alternatively, the excess filler material 12 also be deducted by a squeegee.

5 is a particular application variant of the present invention again. Here is, for example, a spherical or cylindrical (generally: curved) body 15 given. This may, for example, be a drum for the gradient coils of an MRI apparatus. On this body 15 Now, by the 3D printing process, a structure or a structure section 16 printed. The curved body 15 has numerous (microscopic) surface sections whose surface normals are not parallel to each other. All of these surface sections or part of them are now additively applied by 3D printing. First, immediately on the main body 15 one or more layers applied in the direction of the respective surface normal. In the further course serve the original main body 15 together with the already applied layers 17 as a new basic body on which new surface sections have formed. It can then be applied again in the newly resulting spatial directions more layers. In the example of 5 The last layers are then no longer directly on the body 15 imprinted, but on the already printed layers 17 in a completely different direction than the surface normals of the original body 15 that are affected by the pressure point.

In 6 Now, a device is shown, with the example, the pressure according to 2 is feasible. A 3D printer 18 is by a robot 19 added. The robot 19 has multiple axes to make it an object 3 can hold in the desired or predetermined position. A gripper 20 of the robot 19 would be displaceable and rotatable in several or all spatial directions. The gripper 20 holds the object 3 on the half-printed picture 1 ,

The 3D printer 18 now prints more layers 21 at the differently oriented surface portions of the body (ie structure 1 together with object 3 ) on.

The 3D printer 18 preferably has a 5-axis printhead 4 , The printhead 4 is thus movable relative to the main body in almost all spatial directions or pivotable. To these five axes can also be a lifting table 22 be calculated, the workpiece linearly downwards or upwards as indicated by arrow 23 moves.

A control of the 3D printer 18 should be communicative with a controller of the robot 19 be networked to allow collision-free operation. Thus, a respective bypass by collision detection would be feasible. An additional backup by means of image processing or position detection via scanning here would be optional.

Disadvantages resulting from plastic-to-metal (e.g., thermal fusion) bonding are obviated by the method of the present invention, for example, by placing metallic elements in semi-finished printed structures and then imprinting them. Likewise, all other components that serve to improve mechanical and electrical properties can be printed in the respective structure. Such may, for example, serve as a receiving element / support (bearing) for other components, e.g. Covering parts or interfaces. This allows networking with neighboring structures.

In 3D printing, material can be applied from a liquid or gaseous phase. Once the printed material has cured, it can then be printed further using one of the methods presented above. Thus, for example, a placement robot can be used to take at defined times at defined locations components from a magazine and to keep for the intended pressure to the respective predetermined location.

Claims (14)

Method for producing a three-dimensional structure by - providing a basic body ( 1 . 3 ) with a first surface section ( 6 ) having a first surface normal and a second surface portion ( 7 ), whose second surface normal is not parallel to the first surface normal, - application of several layers ( 8th . 9 . 11 . 13 . 17 . 21 ) on the first surface section ( 6 ) each perpendicular to the first surface normal by a 3D printing process, characterized by - applying a plurality of layers ( 8th . 9 . 11 . 13 . 17 . 21 ) on the second surface section ( 7 ) each perpendicular to the second surface normal through the 3D printing process. A method according to claim 1 or the preamble of claim 1, characterized in that - When applying a cup-shaped structure ( 1 ) arises, - in the bowl-shaped structure ( 1 ) a flowable filling material ( 12 ), - into the filling material ( 12 ) an object ( 3 ) is pressed so that it is relative to the bowl-shaped structure ( 1 ) reaches a predetermined position, - the filling material ( 12 ) is such that it is the object ( 3 ) holds in the predetermined position at least partially, and - then further layers ( 8th . 9 . 11 . 13 . 17 . 21 ) on the bowl-shaped structure ( 1 ) and the object ( 3 ) are applied by the 3D printing method. A method according to claim 1 or the preamble of claim 1, characterized in that - the base body is produced by the fact that by the 3D printing process, a structure ( 1 ) is printed, in / on which an object ( 3 ) is inserted or applied in a form-fitting manner. Method according to claim 1 or the preamble of claim 1, characterized in that - an object ( 3 ) on the applied layers ( 8th . 9 . 11 . 13 . 17 . 21 ) from a robot ( 19 ) is held in a predetermined position and - then further layers ( 8th . 9 . 11 . 13 . 17 . 21 ) by the 3D printing process on the already applied layers ( 8th . 9 . 11 . 13 . 17 . 21 ) and the object ( 3 ) are applied in the predetermined position. Method according to one of claims 2 to 4, wherein the object ( 3 ) of layers applied by the 3D printing process ( 8th . 9 . 11 . 13 . 17 . 21 ) is completely or partially enclosed. Method according to claim 2, wherein after the object has been impressed ( 3 ) in the filling material ( 12 ) excess filler material ( 12 ) or by a vacuum robot ( 14 ) is sucked off. Method according to one of the preceding claims, wherein the plurality of layers ( 8th . 9 . 11 . 13 . 17 . 21 ) consist of at least two different materials, and each material separately from a respective robot arm ( 10 ) is applied. Method according to one of the preceding claims, wherein the 3D printing method comprises a spraying, gluing, UV-polymerizing, sintering or welding. Method according to one of the preceding claims, wherein the basic body ( 15 ) is rotated in the 3D printing process. Method according to claim 9, wherein the basic body ( 15 ) is cylindrical and is rotated about its longitudinal axis. Method according to one of the preceding claims, wherein the three-dimensional structure is a bobbin of an MRI apparatus. Device for producing a three-dimensional structure according to a method according to one of the preceding claims. Apparatus according to claim 11, comprising a 5-axis printhead ( 4 ) for the 3D printing process. Apparatus according to claim 12 or 13 with reference to claims 2 to 11, which comprises a multi-axis robot ( 19 ), which is used to hold the object ( 3 ), regardless of the printhead ( 4 ) having.

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