DE102021123264A1 - Additive manufacturing process to produce a workpiece and 3D printer - Google Patents

Abstract

The invention relates to an additive manufacturing method for producing a workpiece (42), with the steps: (a) layer-by-layer curing of liquid or granular printing starting material (14) using a 3D printer (10), so that the workpiece (42) is created. According to the invention, an enveloping structure (44) is built up in layers, which surrounds the workpiece (42) at least in the horizontal direction.

Description

The invention relates to an additive manufacturing method for producing a workpiece with step (a) gradual curing of liquid or granular printing starting material, so that the workpiece is created, using a 3D printer. According to a second aspect, the invention relates to a 3D printer with (a) a print starting material introduction device for producing a layer of print starting material in a working space of the 3D printer, (b) a curing unit for curing the print starting material and (c) a control unit which is designed to automatically drive the pressure starting material introducing device and the curing unit, so that a workpiece of a predetermined shape is produced.

An additive manufacturing process is understood to mean a process in accordance with DIN EN ISO 52911, as of January 1st, 2021. In such methods, the workpiece is built up by the incremental solidification of liquid or granular print feedstock. An additive manufacturing process can be a 3-print process. The advantage of an additive manufacturing process is that very complex components can be manufactured. In particular, components can be manufactured that cannot be produced by machining. Another advantage of additive manufacturing processes is that the individual production of components is made easier.

The often comparatively high costs are a disadvantage of additive manufacturing processes. This is particularly true when large components are to be manufactured. As a first disadvantage, large components lead to a long production time, as a second disadvantage, they require expensive 3D printers with a large working area. The first disadvantage can be reduced by applying semi-finished products, for example by cutting, to the additional structures.

The invention is based on the object of specifying an improved additive manufacturing method.

The invention solves the problem by means of a generic additive manufacturing method with step (b) of stepwise building up an enveloping structure which surrounds the workpiece in, in particular horizontal, direction.

The invention also solves the problem by a generic 3D printing method, which has the following steps: (a) positioning a raw workpiece relative to the 3D printer, so that a first part of the raw workpiece is arranged within a working space of the 3D printer and a second part of the raw workpiece protrudes from the working space, (b) sealing a transition area between the raw workpiece and the 3D printer and (c) 3D proof printing, in particular by means of powder-based 3D printing, of a workpiece part on the raw workpiece, so that the workpiece is created. It is favorable, but not necessary, if this additive manufacturing method has the step of building up the enveloping structure step by step, which surrounds the workpiece in a particularly horizontal direction.

The invention also solves the problem with a generic 3D printer, in which the control unit is designed to automatically build up an envelope structure in layers, which surrounds the workpiece in the horizontal direction.

A 3D printer is a device for additive manufacturing. The term additive manufacturing system could therefore also be used instead of the term 3D printer.

In addition, the invention solves the problem with a generic 3D printer that (a) has a base that has a through-opening, wherein (b) the through-opening is designed in such a way that a raw workpiece can be arranged in such a way that it can be connected to a Part protrudes from the working space of the 3D printer and is arranged with another part in the working space. It is favorable, but not necessary, if the control unit of this 3D printer is designed for the automatic, step-by-step construction of the envelope structure that surrounds the workpiece in the horizontal direction.

The advantage of the invention is that components can be manufactured that are larger than the working space of the 3D printer. Of course, components that fit into the workspace of the 3D printer can also be manufactured.

It is advantageous that when building up an enveloping structure, the starting material for printing can be enclosed between the enveloping structure and the workpiece. If the printing starting material, as provided according to a preferred embodiment, is a metal powder, a health hazard to people from this metal powder cannot be ruled out. This applies in particular if, as provided according to a preferred embodiment, a respirable or carcinogenic pressure starting material is used. The metal powder is enclosed by the enveloping structure and can be removed from the structure in a method step provided according to a preferred embodiment.

It is also advantageous that a 3D printer according to the invention for repairing components on site, i.e. at or near their place of use. This is particularly advantageous if the component can only be moved with great effort, or if it is a component of a system installed in the sea. This can be, for example, a drilling platform or a wind turbine.

The invention relates in particular to the special case that a 3D printer, i.e. a machine for additive manufacturing, can produce components that are larger in the construction direction than the construction space. The installation space must be sealed off from the environment for most processes. An inventive solution preferably includes a seal, preferably a co-printed seal. In addition, print starting material can be printed onto existing components. In this case, a fitting piece, in particular a printed one, adapts to the component and can create an initial seal. This printed fitting, which could also be called a seal, can then be used again. In additive manufacturing, a construction platform can be lowered. The construction platform is a component on which the resulting workpiece is arranged. The seal can also function as an intermediate floor.

In the context of the present description, the working space of the 3D printer is understood to mean that spatial area in which the starting material for printing can be cured automatically by the 3D printer.

Curing is understood to mean, in particular, a process in which the printing starting material is at least partially melted, sintered or polymerized. Preferably the curing is laser beam melting.

Sealing is understood in particular to mean that the passage of pressure starting material and/or gas is prevented.

It is favorable if, while the additive manufacturing process is being carried out, the starting material for printing is located both between the enveloping structure and the workpiece and outside the enveloping structure, but within the working space of the 3D printer. It is favorable to remove the pressure starting material from the working space, for example by suction, before removing the workpiece and the enveloping structure.

Preferably, starting material for printing is located between the enveloping structure and the workpiece during the additive manufacturing process. It is favorable, alternatively or additionally, to remove the starting material from the area surrounded by the enveloping structure.

It is favorable if the additive manufacturing method includes the step of closing the enveloping structure, so that the enveloping structure forms an envelope that is impervious to the print starting material. It is then possible to remove the print object, consisting of the workpiece and the enveloping structure, from the 3D printer without the risk of the print starting material escaping into the environment. In addition, the enveloping structure can form a protection for the printed component. The shell structure is closed by curing the printing starting material, so that the closed shell is formed.

The enveloping structure is preferably connected directly or indirectly to the workpiece. In particular, the enveloping structure is materially connected to the workpiece. For example, the enveloping structure and the workpiece form a one-piece object. A one-piece object is understood to mean an object that only has joints that did not arise during the curing of the printing starting material.

The enveloping structure preferably has a prismatic enveloping structure outer contour. The outer contour of the enveloping structure can, for example, be in the form of a cylinder jacket or have the cross section of an, in particular regular, n-gon.

The method preferably comprises the steps: (a) building up at least one layer, in particular a plurality of layers, of the printed object, and (b) moving part of the printed object out of the working space of the 3D printer, the printed object partially remaining in the working space. These steps can preferably be repeated two, three or more times until the workpiece is completed.

A seal is preferably arranged between a working space wall of the working space of the 3D printer and the enveloping structure. This seal prevents the pressure starting material from escaping from the working space.

It is favorable if the method has the steps (a) building up at least one layer, in particular a plurality of layers, of the printed object and (b) moving the seal in the building direction. Alternatively or additionally, the method can include the step of displacing the printed object together with the seal, so that the printed object is moved further out of the working space.

In particular, the seal can be movable relative to the working space wall, but this is not necessary. The gasket is preferably positioned below a base surface on which the first layer placed on print stock. The seal can be designed as a screen.

The gap between the workpiece and the 3D printer is preferably closed by means of a screen. A panel is a component whose inner contour can be changed automatically and non-destructively. For example, the aperture has movable slats. The lamellas adapt to the outer contour of the workpiece. If the workpiece is at least partially moved out of the working space, the workpiece moves relative to the panel.

Alternatively or additionally, the space between the workpiece and the 3D printer is sealed by means of an elastic seal. The elastic bond is constructed from an entropy-elastic material, for example.

It is also possible, but not necessary, for at least part of the print starting material to be removed from the working space before the seal is displaced relative to the printed object and/or to the 3D printer.

It is advantageous if, after the seal has been displaced, a gap area between the enveloping structure and the working space wall is sealed. This can be done, for example, by means of a solder, by means of wax or an expansion cushion, for example a hydro-expansion cushion.

The sealing preferably comprises the steps of attaching a fitting, in particular a screen, to the workpiece so that a connection between the fitting and the workpiece is sealed for pressure starting material. The adapter is preferably designed to be movable relative to the working space and/or to the enveloping structure.

Manufacturing the fitting preferably includes 3D printing the fitting. This preferably has the steps: (a) detecting an outer contour cross-section of a workpiece outer contour of the raw workpiece and (b) producing a fitted piece with a fitting contour which corresponds to the workpiece outer contour. The adapter is preferably attached to the workpiece in such a way that a tight connection is created for the print starting material. It is favorable if the print starting material lies directly or indirectly on the fitting piece during printing. This means in particular that the adapter absorbs at least 50% of the weight of the printing starting material that is arranged vertically above it. The fitting can be produced, for example, by 3D printing and/or by cutting and/or machining. For example, water jet cutting is suitable.

The fitting piece can also serve as the basis for the enveloping structure. The enveloping structure is therefore preferably applied to the fitting piece in a rigid manner relative to the fitting piece. It is possible, but not necessary, for the enveloping structure to be in direct contact with the fitting.

The 3D printer according to the invention preferably has a base that has a through-opening. The through-opening is preferably designed in such a way that a raw workpiece can be arranged in such a way that part of it protrudes out of the working space of the 3D printer, in particular downwards, and another part is arranged in the working space. It is then possible and provided according to a preferred embodiment to manufacture components that are larger than the abdomen of the 3D printer.

According to a preferred embodiment, the 3D printer has a seal, in particular a screen and/or a seal made of entropy-elastic material, which is arranged to seal the working space of the 3D printer against the workpiece or object protruding through the through-opening. The seal preferably prevents pressure feedstock and/or gas from passing through. In particular, the seal is pressure starting material-tight and/or gas-tight.

The finished workpiece and/or the printed object preferably has a maximum extent that is greater than the maximum extent of the working space. In particular, the finished workpiece and/or the printed object has a maximum extension of at least 500 mm, in particular at least 750 mm. Such large objects cannot be produced with previous 3D printers.

The 3D printer preferably has a seal which is designed to seal off a transition area between the raw workpiece and the 3D printer.

It is favorable if the 3D printer has a discharge chute that has a discharge chute inner contour and the discharge chute inner contour corresponds to a fitting piece outer contour. The fitting piece can then slide in the discharge chute, thereby partially moving the raw workpiece out of the 3D printer's workspace.

The discharge chute has a discharge chute length that is preferably at least 2 centimeters, in particular at least 10 centimeters. The effect of this is that the workpiece can be built up by approximately the length of the discharge chute before it has to be partially moved out of the work area.

The print starting material is preferably formed from a metal alloy, preferably a tool steel, a nickel-based alloy or a cobalt-chromium alloy. The printing starting material can also be plastic.

A particle size of the printing starting material is preferably at least 25 μm, in particular 35 μm, and/or at most 75 μm, in particular at most 45 μm, for example 45±5 μm.

• 1 in 1a eine perspektivische, teilweise geschnittene Ansicht eines erfindungsgemäßen 3D-Druckers zum Durchführen eines erfindungsgemäßen Verfahrens gemäß einer ersten Ausführungsform und in 1b eine perspektivische, teilweise geschnittene Ansicht eines erfindungsgemäßen 3D-Druckers zum Durchführen eines erfindungsgemäßen Verfahrens gemäß einer zweiten Ausführungsform,
• 2 in 2b eine Ansicht gemäß 1a zum Beginn eines Verfahrens, bei dem an ein Roh-Werkstück eine Struktur angedruckt wird und in 2b den Zustand am Ende des Verfahrens, und
• 3 einen Querschnitt durch eine Dichtung des 3D-Druckers.

The invention of the accompanying drawings is explained in more detail below. while showing

• 1 in 1a a perspective, partially sectioned view of a 3D printer according to the invention for carrying out a method according to the invention according to a first embodiment and in 1b a perspective, partially sectioned view of a 3D printer according to the invention for carrying out a method according to the invention according to a second embodiment,
• 2 in 2 B a view according to 1a at the start of a process in which a structure is printed onto a raw workpiece and 2 B the state at the end of the procedure, and
• 3 a cross section through a seal of the 3D printer.

1a 12 shows a 3D printer 10 according to the invention, which has a printing starting material introduction device 12 for producing a layer of printing starting material 14 in a working space 16 of the 3D printer 10. In the present case, the printing starting material 14 is a metal powder.

The 3D printer 10 has a curing unit 18, which has a laser 20 for emitting a laser beam 22 and a deflection unit 24 for deflecting the laser beam 22 to a curing point P in the present case. To produce a layer of the workpiece, the starting material for printing is first introduced into the working space 16 by the starting material for introducing the starting material 12 and smoothed out by means of a squeegee 26 of the starting material for introducing the printing material 12 so that the layer is formed. The curing point P is then moved over the layer by means of the deflection unit 24 in such a way that the starting material for printing connects to a raw workpiece 28 that is already present.

A program is stored in a control unit 30, which is connected to the curing unit 18, according to which the curing unit 18 and the pressure starting material introduction device 12 are controlled.

Alternatively, the curing unit 18 can emit a particle beam, such as an electron beam, for example. Instead of the metal powder, it is conceivable that the starting material 14 is a ceramic powder that is locally sintered by means of the curing unit.

It is also possible for the printing starting material to be a liquid, in particular a polymerizable plastic. In this case, the curing unit 18 emits at least two laser beams, both of which pass through the curing point P.

The 3D printer 10 has a workspace wall 32 and a floor 34 surrounding the workspace 16 . The bottom has a through-opening 38 to which a discharge chute 40 is connected. The discharge shaft 40 has a prismatic inner wall. In other words, the cross section of the discharge shaft remains the same over the extent of the discharge shaft 40 .

When carrying out a method according to the invention, a workpiece part 41 is printed onto the raw workpiece 28, for example. The raw workpiece 28 and the workpiece part 41 form a workpiece 42 after the end of the 3D printing process.

1a shows that an enveloping structure 44 is built up around the workpiece 42 . The enveloping structure 44 surrounds the workpiece 42 in the horizontal direction, ie in an xy plane that runs horizontally.

The enveloping structure 44 is arranged on a gasket 46 which seals against the workpiece 42 . In the present case, the seal 46 has a fitting piece 48, the fitting contour of which corresponds in the form of its fitting inner contour to a workpiece outer contour. The seal 46 is connected, in the present case in the area of the fitting piece 48, to the workpiece 42 via a preferably detachable bonded connection. For example, the adapter 48 is soldered to the workpiece 42 .

2a shows the situation 1a . It can be seen that the seal 46 is in contact with an inner surface 50 of the discharge shaft 40 . Using the program that is in the control unit 30 (cf 1a) is deposited, the workpiece part 41 is produced in layers.

The workpiece part 41 and the enveloping structure 44 grow as a result of the successive application of further layers, which is indicated by the dashed lines. In this state, the working space 16 is filled with significantly more print starting material than at the beginning of the 3D printing process, as shown in 1a is shown.

The 3D printer 10 can have a fastening device 52 shown schematically, which is connected to the raw workpiece 28 . The raw workpiece 28 is moved along a direction of extension E of the discharge chute 40 relative to the working space 16 by means of a traversing device 54 . During this movement, the seal 46 slides along the inner surface 50 of the discharge shaft 40. In other words, the workpiece 42 and the enveloping structure 44 are partially pushed out of the working space 16 of the 3D printer 10. A part of the workpiece 42 remains in the work space. In other words, the workpiece 42 is further arranged so that additional print stock can be attached to the workpiece 42 using additive manufacturing.

2 B shows the situation after the move. It is now possible, but not necessary, and represents a preferred embodiment of the invention—regardless of other features of the embodiment described—that the enveloping structure 44 is closed. This is indicated by the dashed circle.

Another seal may be placed between the wrap structure 44 and the inner surface 50 . For example, the seal is an elastomer such as silicone. The print starting material can be toxic. Then it should be reliably prevented from falling out.

The enveloping structure 44 is constructed in such a way that its outer contour of the enveloping structure corresponds to a discharge shaft inner contour of the discharge shaft 40 .

3 shows a schematic cross section through a part of the raw workpiece 28 and the seal 46. The adapter 48 rests against a projection 56 of the raw workpiece 28, which is not cylindrical in this area but, for example, conical.

2 B shows that channels 58.1, 58.2 can be formed in the area of the discharge shaft 40, through which the pressure starting material 14 can be removed, for example sucked off or blown out, from an intermediate space between the inner surface 50 of the discharge shaft 40 and the enveloping structure 44.

The discharge chute has a discharge chute length L, which is preferably at least 10 centimeters. It is then possible to move the workpiece 42 out of the working space 16 by, for example, 0.8 L.

After the end of the 3D printing process, it is advantageous to remove the print starting material 14 within the enveloping structure 44, for example by blowing it out or sucking it off. Thereafter, the enveloping structure 44 can be removed.

1b shows a schematic cross section through a 3D printer 10 according to a second embodiment. In this case, the workpiece 42 is made entirely by additive manufacturing. The workpiece 42 is built on a base 60 and is surrounded by the enveloping structure 44 . The seal 46 will lose contact with the discharge chute 40 as the workpiece 42 moves further out of the work area. A second seal 46 ′ then seals the enveloping structure 44 against the discharge shaft 40 .

Reference List

10

3D printer

12

Pressure feedstock introduction device

14

print source material

16

working space

18

curing unit

20

Laser

22

laser beam

24

deflection unit

26

squeegee

28

raw workpiece

30

control unit

32

workspace wall

34

Floor

38

passage opening

40

discharge chute

41

workpiece part

42

workpiece

44

shell structure

46

poetry

48

fitting piece

50

Inner surface

52

fastening device

54

traversing device

56

head Start

58

channel

60

base

E

direction of extension

P

curing point

Claims (14)

Additive manufacturing method for producing a workpiece (42), with the steps: (a) curing of liquid or granular printing starting material (14) in layers by means of a 3D printer (10), so that the workpiece (42) is produced, characterized by the step: ( b) building up an enveloping structure (44) in layers, which surrounds the workpiece (42) at least in the horizontal direction. Additive manufacturing process claim 1 , characterized by the steps of: (a) closing the enveloping structure (44) so that the enveloping structure forms an envelope which is impervious to the printing starting material (14), and (b) removing printing starting material (14) which surrounds the enveloping structure (44) on the outside, (c) removing the print stock (14) from the envelope structure (44). Additive manufacturing method according to any one of the preceding claims, characterized in that (i) the enveloping structure (44) has a prismatic, in particular cylinder jacket-shaped, enveloping structure outer contour, (ii) the method has the following steps: (a) building up at least one layer, in particular a plurality of layers, the enveloping structure (44) and the workpiece (42), (b) moving a portion of the workpiece (42) and the enveloping structure (44) out of the working space (16) of the 3D printer (10), wherein the workpiece (42) partially remaining in the work space (16), and (c) repeating steps (a) and (b) until the workpiece (42) is completed. Additive manufacturing method according to one of the preceding claims, characterized in that (i) between a working space wall (32) of a working space (16) of the 3D printer, which extends along a direction of construction of the 3D printer (10), and the enveloping structure (44 ) a seal (46) is arranged, and (ii) the method has the following steps: (a) building up at least one layer, in particular a plurality of layers, of the enveloping structure (44) and the target structure, (b) shifting a position of the sealing (46) relative to the enveloping structure (44) in the assembly direction, in particular along the enveloping structure (44), and (c) assembling at least one layer, in particular a plurality of layers, of the enveloping structure (44) and the target structure. Additive manufacturing process claim 4 , characterized by the steps: (a) before the displacement of the seal (46) removal of pressure starting material (14) from an area radially outside the enveloping structure (44), in particular from the working area, and/or (b) after displacement of the seal (46) sealing a gap area between the wrap structure (44) and the gasket (46). Additive manufacturing method according to any one of the preceding claims, characterized by the steps of: (a) positioning a workpiece (42) relative to a 3D printer such that a first part of the workpiece (42) is arranged within a working area of the 3D printer (10). and a second part of the workpiece (42) protrudes from the work area, (b) closing a gap between the work piece (42) and the 3D printer (10), so that a work space (16) is created which is closed at least at the bottom, and (c ) 3D proof printing, in particular by means of powder-based 3D printing, of a workpiece part (41) on the workpiece (42). Additive manufacturing process claim 6 , characterized in that the sealing comprises the following steps: (a) attaching a fitting (48) to the workpiece (42) so that a connection between the fitting (48) and the workpiece (42) for print starting material (14) is tight, (b) the fitting (48) being movable relative to the work area. Additive manufacturing process claim 7 , characterized by the steps: (a) detecting an outer contour cross-section of a workpiece outer contour of a workpiece (42) to be repaired, (b) producing a fitting piece (48) with a fitting contour which corresponds to the workpiece outer contour, and (c) attaching the Fitting piece (48) on the workpiece (42), so that a connection which is sealed for the printing starting material (14) is created, (d) the printing starting material (14) being applied to the fitting piece (48). Additive manufacturing process according to one of Claims 6 until 8th characterized in that the enveloping structure (44) is applied to the fitting (48) rigidly relative to the fitting. Additive manufacturing process according to one of Claims 6 until 9 , characterized in that the 3D printer (10) has a discharge chute (40) which has a discharge chute inner contour and that the discharge chute inner contour corresponds to a fitting outer contour. 3D printer (10) with (a) a printing starting material introduction device (12) for producing a layer of printing starting material (14) in a working space (16) of the 3D printer (10), (b) a curing unit (18) for curing the pressure starting material (14), (c) a control unit (30) which is designed to automatically control the pressure starting material introduction device (12) and the curing unit (18) so that a workpiece (42) of a predetermined shape is produced, characterized in that that (d) the control unit (30) is designed to automatically carry out a method with the step: building up an enveloping structure (44) in layers, which surrounds the workpiece (42) in the horizontal direction. 3D printer (10) after claim 11 , characterized by (a) a base (34) having a through-opening (38), (b) the through-opening (38) being formed such that a workpiece (42) can be arranged in such a way that it can be connected to a part from the Working space (16) of the 3D printer (10) protrudes and another part in the working space (16) is arranged. 3D printer (10) after claim 11 or 12 , characterized by (a) a discharge chute (40) which has a prismatic discharge chute inner surface, (b) the discharge chute inner surface has a cross section with a discharge chute inner contour, (c) the through-opening (38) is formed on the discharge chute (40). and (d) the 3D printer (10) has a fitting (48) which has a fitting outer contour which corresponds to the discharge chute inner contour and has a recess for enclosing a workpiece (42). 3D printer (10) according to one of the Claims 11 until 13 , characterized by (a) a fastening device (52) for fastening the 3D printer (10) to a workpiece (42) and/or (b) a print starting material discharge device for removing print starting material (14) from the working space (16). PI/be

Images