DE102017202224A1 - Filament and printhead for 3D printing and 3D printing - Google Patents

Abstract

The invention relates to a filament (1) for 3D printing in which a 3D printable material (3) surrounds an electrically conductive wire (2). It also relates to a printhead (4) for a 3D printer having a severing device (9) for severing such a filament (1). It also relates to a 3D printing method for producing a three-pronged structure (5) having a plurality of printheads, wherein a first of the printheads is fed with such a filament (1) while at least a second one of the printheads is being fed with another filament, and at in that the first print head (4) prints an electrical conductor track of the structure (5) and at least the second print head prints a further part of the structure (5), in particular the remaining part of the structure (5).

Description

The invention relates to a filament for 3D printing and a print head for a 3D printer and a 3D printing process.

Additive manufacturing is a process in which a three-dimensional structure is built up layer by layer on the basis of digital 3D design data by depositing material. This is also referred to as three-dimensional printing, 3D printing for short. As a result, conventionally unfinished three-dimensional structures can be produced.

A 3D printer or a print head for this is from the DE 102014226425 A1 known.

In the known free-space method FDM (Fused Deposition Modeling), a filament made of plastic is melted by means of a heated nozzle and the component is built up in layers from the melt strand. Currently, it is not possible to incorporate continuous, low-resistance electrical conductors or strands into the component by means of 3D printing. Although electrically conductive filaments are known by means of which electrically conductive structures in 3D printing can be generated. However, this filament and the structures produced therefrom are relatively high-impedance. Thus, no high electrical power can be transmitted with it.

As a result, it is usually only later that electrical printed conductors are inserted into the finished printed structure or laid externally on it. To insert the electrical conductors, cavities are already provided in the structure during printing or incorporated subsequently. However, this procedure is complex and does not fully exploit the potential of 3D printing.

The object of the present invention is to improve the state of the art.

This object is achieved by the objects specified in the main claims. Preferred embodiments thereof are the dependent claims.

Accordingly, a filament for 3D printing is proposed. This is characterized by having an electrically conductive wire surrounded by 3D printable material. The electrically conductive wire thus forms the core of the filament, while the 3D-printable material forms the envelope for this purpose. The wire is thus embedded in the 3D printable material. Such a filament forms the starting material for a 3D printing process.

The 3D printable material of the filament can in particular be melted by a conventional print head of a 3D printer or otherwise applied to a three-dimensional structure. The 3D-printable material may in particular be a thermoplastic, if the filament is to be used for 3D printing in the FDM (Fused Deposition Modeling) method. However, it can also consist of another 3D printable material, depending on which 3D printing process the filament is intended for.

The electrically conductive wire is in particular in the form of a solid wire, ie in the form of a single fiber of solid material. Or it is in the form of a strand, ie in the form of a plurality of parallel fibers of solid material. In particular, the wire consists of a good electrical conductor such as copper or aluminum or silver (this includes corresponding alloys thereof). Litz has the advantage that the filament is more flexible in 3D printing. However, there is a risk that it will unintentionally fray during 3D printing.

Preferably, the melting point of the wire is above that of the 3D printable material. This prevents the wire from undesirably melting during 3D printing in the FDM process instead of the surrounding material. In particular, the melting point of the wire is therefore significantly higher than that of the 3D printable material, for example> 100 ° C. In particular, the melting point of the wire is above the usual operating temperature of a printhead used for 3D printing in the FDM process.

Preferably, furthermore, the wire extends continuously along the entire length of the filament. The wire in the unprocessed filament thus has no interruptions, which would affect its electrical conductivity. Thus, particularly long low-resistance electrical conductor tracks can thus be formed in a three-dimensional structure.

Preferably, the 3D printable material is an electrical insulator. The material may in particular be a polymer. Thus, during processing of the filament in 3D printing, an insulating embedding for the wire in the printed structure can be easily created.

The filament is particularly useful for making electrical traces in 3D printing within a single printed layer of the printed structure. To overcome multiple print layers with a continuous electrical trace, it is advantageous if the 3D printer used for printing has multiple (at least two) print heads. One of the printheads then serves for printing the proposed conductive filament within the structure while the one or more other printheads are for printing the remaining structure. In order to pass through a continuous strip conductors through one or more print layers, the environment around the printed circuit penetrating electrical conductor track or the wire is thus printed by means of the or the other print heads around. This procedure is also proposed in the 3D printing process explained below again.

Also proposed is a printhead for a 3D printer. This is characterized by a severing device for severing the proposed filament with the wire embedded in the 3D printable material. Namely, since the mechanical properties of the wire (particularly, in terms of strength, melting point, etc.) are usually significantly different from those of the 3D printable material, there is the problem that the filament is not readily severable by a common 3D printing printhead. The special severing device designed to sever the wire embedded in the filament solves this problem.

Preferably, the severing device is designed for mechanically or thermally severing the filament. In particular, the severing device can thus have a device for shearing off or pinching or cutting through the filament with the wire, or a device for dry firing (cutting firing).

Preferably, the print head has a reflow device for melting the 3D printable material of the filament. It is provided that the severing device is located in the outlet direction of the melting device for the melted 3D printable material. The severing device lies, as it were, where the melt strand of the molten filament flows after melting, for example below the melting device. By this measure, the (molten) filament can be separated very exactly where an electrical conductor formed by the wire therein should end. Such a print head thus serves in particular for 3D printing with a meltable material, for example in the FDM process.

Also proposed is a 3D printing process for creating a three-dimensional structure. The printing process is done with multiple printheads. At least a first of the printheads is loaded with the above-proposed filament comprising the wire and the 3D printable material. This printhead prints with this electrically leifähigen filament. This first printhead is preferably the above-proposed printhead with the severing device. At least a second of the print heads is fed with another filament, in particular a filament of 3D printable solid material. This printhead then prints with the other filament. The first printhead is now used to print an electrical trace of the structure. At least the second printhead then prints another part of the structure, in particular the remaining part of the structure. Thus, a continuous, electrically conductive trace can be formed in the structure, which can also penetrate a plurality of printed layers of the structure.

• 1 ein Filament für 3D-Druck,
• 2 ein Druckkopf für 3D-Druck.

In the following the invention will be explained in more detail with reference to figures, from which further preferred embodiments and features of the invention can be removed. Shown schematically in each case:

• 1 a filament for 3D printing,
• 2 a printhead for 3D printing.

The filament 1 according to 1 serves as starting material for 3D printing. It has a core made of an electrically conductive wire 2 on, as well as a the wire 2 surrounding case made of 3D printable material 3 For example, from a thermoplastic. The 3D-printable material 3 is in particular an electrical insulator. The filament can be wound up on a roll. The wire 2 has a much higher melting point than the 3D printable material 3 , The wire 2 can consist of solid material, in particular solid metal, or strand, in particular metal strand. The material of the wire 2 may in particular be copper.

The printhead 4 according to 2 is used to perform a 3D printing process, such as in particular the FDM process, so for the production of a three-dimensional structure 5 , The starting material for 3D printing is a filament 1 with 3D printable material.

The structure 5 is created by adding the starting material additively in multiple print layers through the printhead 4 on the printing table 6 or that there already existing material is applied. This is the printing table 6 and / or the printhead 4 movable on the side and in height (see arrows on the printing table 6 ).

The printhead 4 has a melting device 7 to melt the 3D printable material. If the filament 1 according to 1 used for 3D printing is the melting device 7 to set up only the 3D-printable material 3 of the filament 1 to melt, not but the wire contained therein 2 , The wire 2 then serves in particular for generating an electrical conductor in the structure 5 , The filament 1 leaves the melting device 7 in the form of a filamentary melt strand in which the material 3 is melted and (if present) the wire 1 is fixed.

The printhead also has a conveyor 8th to the printhead with the filament 1 to feed, so the filament 1 the melting device 7 supply. The conveyor 8th For example, it may include rollers or wheels that support the filament 1 between them and by a rotary movement (see arrows on the conveyor 8th ).

The printhead 4 furthermore has a severing device 9 for severing the from the melting device 7 liquefied filaments 1 , The severing device 9 In the present case, this is exemplified by two opposing cutting edges which are designed to be able to be driven. The severing device 9 is so executed and in the printhead 4 arranged that when closing the cutting both the liquefied material 3 , as well as the existing wire 2 be severed. The severing device 9 So lies in the outlet direction of the melting device 7 for the molten filament 1 , Thus, the wire can 2 exactly at the place of the structure 5 be severed, where the thus formed electrical trace of the structure 5 should end.

It can be provided that several such or comparable printheads 4 be used in a 3D printer. Thus, without transection of the wire 2 an uninterruptible electrical trace extending across multiple print layers in the structure 5 be generated. This will be one of the printheads 4 with the filament 1 according to 1 fed to the production of the electrical trace, while the or the other printheads are fed with a filament of pure 3D-printable material. The former printhead 4 then generates the electrical trace while the one or more other printheads are the remaining parts of the structure 5 generate, so around the electrical trace parts lying around the structure 5 ,

LIST OF REFERENCE NUMBERS

1

filament

2

wire

3

3D printable material

4

printhead

5

structure

6

printing table

7

reflow

8th

conveyor

9

By separating device

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 102014226425 A1 [0003]

Claims (9)

Filament (1) for 3D printing, characterized by an electrically conductive wire (2) surrounded by 3D printable material (3). Filament (1) after Claim 1 wherein the wire (2) is made of solid wire or stranded wire. Filament (1) after Claim 1 or 2 wherein the melting point of the wire (2) is above that of the 3D printable material (3). Filament (1) according to one of the preceding claims, wherein the wire (2) extends continuously over the entire length of the filament (1). The filament (1) of any one of the preceding claims, wherein the 3D printable material (3) is an electrical insulator. A printing head (4) for a 3D printer, characterized by a severing device (9) for severing a filament (1) for 3D printing according to any one of the preceding claims. Printhead (4) to Claim 6 wherein the severing device (9) is designed for mechanically or thermally severing the filament (1). Printhead (4) to Claim 6 or 7 , with a melting device (7) for melting the 3D printable material (3) of the filament (1), wherein the severing device (9) in the exit direction of the reflow device (7) for the melted 3D printable material (3). 3D printing method for producing a three-dimensional structure (5) with a plurality of printheads, wherein a first of the printheads, in particular a printhead (4) according to one of the Claims 6 to 8th , with a filament (1) according to one of Claims 1 to 5 is charged while at least a second of the printheads is fed with another filament, wherein the first printhead (4) prints an electrical trace of the structure (5) and at least the second printhead prints another part of the structure (5), in particular the remaining one Part of the structure (5).

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