WO2019137976A1

WO2019137976A1 - Method and device for producing objects from metal

Info

Publication number: WO2019137976A1
Application number: PCT/EP2019/050495
Authority: WO
Inventors: Pierre Joseph SCHMITZ
Original assignee: Schmitz Pierre Joseph
Priority date: 2018-01-10
Filing date: 2019-01-10
Publication date: 2019-07-18
Also published as: LU100676B1

Abstract

The invention relates to a method and a device for producing an object from metal, wherein: - a metal wire is progressively welded on in spots or in segments layer by layer by means of a wire-carrying primary electrode in a resistance welding process; - a channel extends through the main body of the wire-carrying primary electrode, through which channel the metal wire is fed in the solid state, the metal wire being bent in a very small bending radius in or directly below the opening of said channel through which the metal wire is led out of the wire-carrying primary electrode, in order to apply the metal wire flat by sliding the lower contact surface of the wire-carrying primary electrode over the metal wire below the opening of the channel, the metal wire being laid out on an adjacent metal surface and being welded on in spots; - the metal surface is a carrier plate or a metal wire layer already previously applied, the method comprising the following steps: (a) for resistance welding in spots and in segments, conducting an electric current pulse from the wire-carrying primary electrode through the metal wire to the adjacent metal surface, (b) moving the wire-carrying primary electrode relative to the metal surface and simultaneously laying out a length of metal wire corresponding to the movement onto the adjacent metal surface, (c) repeating steps (a) and (b) in order to form the object from metal layer by layer by means of successive welds and movements. In addition to said steps, the method also optionally comprises the following step: (d) conducting a further electric current from a secondary electrode through metal wire already welded on in spots and in segments by means of steps (a) and (b), in order to at least partially additionally heat up said metal wire, preferably over the entire length laid out in one or more of steps (b), and to connect said metal wire more strongly to the adjacent metal surface or even to fuse said metal wire with the metal surface, and optionally to completely melt said metal wire with the metal surface.

Description

METHOD AND DEVICE FOR PRODUCING ARTICLES OF METAL

Technical area

The present invention relates generally to a method and apparatus for making articles of metal.

State of the art

In the world of additive manufacturing methods, there are different devices to produce metal objects. The dominant methods are selective laser sintering and selective laser melting. For this purpose, there is the method of applying metal by resistance welding by means of a movable electrode to an object as described in the patent US 6443352. In this case, metal is connected to one another by the heat generated by the flow of current in the metal at the contact surface with the already applied metal. This method implements a wire electrode that applies metal wires to three-dimensional objects, and 3D printers that use this method are not available for the general household, unlike other plastic 3D printers that are available in abundance.

Today's metal 3D printers prove to be complex, expensive and cumbersome devices. In contrast to the plastic FDM 3D printers, which already have a large number of people at home, they are unsuitable for the masses of people. The available so-called desktop 3D printers can mainly produce only plastic objects with low strength and temperature resistance compared to metals. Printing a metal object for a wide variety of applications is too expensive and cumbersome for most people and therefore out of the question.

Object of the invention

An object of the present invention is therefore to provide a method and a corresponding device with easy-to-use technique that allow to produce metal objects in good quality and strength and also are inexpensive. In addition, a corresponding device should be relatively small and lightweight to space, building material and thus save costs.

General description of the invention

This object is achieved according to the invention in a first aspect by methods for producing an article of metal a metal wire progressively in layers by means of a wire-carrying primary electrode in the resistance welding process stretched or spot welded,

wherein through the main body of the wire-guiding primary electrode, a channel passes through which the metal wire is guided in the solid state and led out into or directly below the mouth of this channel through which the metal wire from the wire-guiding primary electrode, laid out on an adjacent metal surface and stretched or Welded pointwise

wherein the metal surface is a carrier plate, or a previously attached metal wire layer,

the method comprising the steps of:

(a) for stretch or spotwise resistance welding, passing an electric shock from the wire-guiding primary electrode through the metal wire to the adjacent metal surface;

(b) moving the wire-guiding primary electrodes relative to the metal surface and simultaneously laying out a length of metal wire corresponding to the movement on the adjacent metal surface,

(c) repeating steps (a) and (b) to form the article of metal in layers by subsequent line or spot welds and movements;

and wherein, in addition to these steps, the method further comprises, optionally, the step of:

(D) passing a further electric current from a secondary electrode by means of steps (a) and (b) already stretched or point welded metal wire around this at least partially in addition, preferably on the entire in one or more of the steps (b) designed length to heat up and merge with the adjacent metal surface, ie To connect stronger by resistance welding or even to merge with this possibly completely melt it.

Preferably, the metal wire is bent laterally during laying out at the mouth of the channel of the wire-guiding primary electrode during step (b). More preferably, the metal wire is bent at a very small centerline radius, eg 0.5 ^* q <centerline radius <3 ^* q, where q is the diameter of a round wire or the width / thickness of a different shaped wire to make it flat by sliding over the lower one Apply contact surface of the wire-guiding primary electrode below the mouth of the channel, wherein the metal wire to the adjacent Metal surface, ie the support plate, or on a previously attached metal wire layer, placed.

The bending of the metal wire can be done on the one hand by guiding and friction along the mouth of the wire-guiding primary electrode. The mouth may comprise or consist of a different material from the body. Particularly preferably, the different material is a ceramic material or a different / different from the base metal.

On the other hand, the bending of the metal wire can also be done by heating the metal wire and moving the wire-carrying primary electrode.

The channel of the wire-guiding primary electrode can be closed laterally, i. be tubular. In other embodiments, however, the channel may also be open and correspond to a notch attached laterally to the body through which the metal wire is passed and which terminates in an orifice to the bottom surface of the wire-carrying primary electrode.

The mouth of the channel of the wire-guiding primary electrode preferably comprises an annular contact surface. Under such a contact surface of the metal wire can advantageously rotate around the orders in order to apply it in any direction of a plane can. The contact surface is preferably configured such that it can transmit at least a portion of the current from the wire-guiding primary electrode to the metal wire.

[001 1] In a preferred embodiment, the channel of the wire-guiding primary electrode is wider (in and short) above the mouth than the remainder of the channel so as to facilitate or allow the metal wire to bend, thereby ensuring that the wire-carrying primary electrode with the lowest contact surface can rest on the wire. More preferably, the wider portion extends for a length from the lowest end of the mouth of the channel as seen along the centerline of the channel, which may be between 0 and 4 * q, where q is the wire diameter of one round wire or the width / thickness of another shaped one Wire is.

Alternatively, the wire-carrying primary electrode may also apply the metal wire without resting on the bottom surface of the top of the metal wire.

Advantageously, the metal wire is preheated by means of a wire leading primary electrode upstream, second electrode by conducting a second current (shock). For this purpose, the second electrode is preferably arranged inside the main body of the wire-guiding primary electrode. During the process, the guidance of the metal wire through the channel by a motorized feed, preferably by adhesion via rollers, are supported.

The cross section of the metal wire may be round or any other shape. An embodiment sees e.g. that before the introduction of the metal wire in the wire-guiding primary electrode whose cross-section, preferably by rolling, is changed.

The movement of the wire-guiding primary electrode relative to the carrier plate is designed so that it can be performed in three dimensions, wherein in step (b) either only the wire-carrying primary electrode, or only the carrier plate, or both are moved. For example, For example, the primary electrode may be movable in only one (vertical, Z) direction, in which case the carrier plate is movable in the other two (X and Y) directions. In another variant, the carrier plate is firmly mounted and the primary electrode can be moved in all three directions.

Advantageously, in step (d), a pressure is exerted on the heated metal wire to press the underlying, in the case of at least partially melted metal wire, metal wire flat, for example.

The electrical opposite pole of the secondary electrode is usually the carrier plate. In an advantageous embodiment, the opposite pole can also be one or more further counter-pole secondary electrode (s) which can be placed on the metal object.

Preferably, the mouth of the wire-guiding primary electrode, if necessary, or the tip of the secondary electrode can be reground automatically if necessary, particularly preferably by means of a grinding surface adjacent (i.e., in the vicinity of the corresponding electrode and within the range of its movement unit).

The method may further comprise a step of additionally shaping the article of metal during and / or after its completion, e.g. by means of a movably arranged metal-removing tool, preferably a movably arranged grinding surface or a movably arranged milling cutter.

The metal wire is usually a wire made of a metal or a metal alloy. In some cases, it is advantageous that such a metal wire additionally comprises a sheath with fusible solder material, wherein the solder material has a melting temperature which is expediently below that of the metal wire.

The metal object is released after the completion of the support plate and can then be removed. In a second aspect, the invention relates to a device for producing articles of metal by progressively layered orders and

Resistance welding of a metal wire. For this purpose, the device comprises means which are suitable for carrying out the method or are adapted / configured.

In a further aspect, the invention relates to a device for the production of articles of metal by progressively layered orders and

Resistance welding of a metal wire, the apparatus comprising:

a power supply designed to generate electrical surges for resistance welding,

a wire-guiding primary electrode for guiding and spot-wise or section-wise resistance welding of a metal wire, wherein the wire-carrying primary electrode is connected to the power supply,

a carrier plate for receiving the article to be made of metal, wherein the carrier plate is connected to the power supply,

optionally a secondary electrode, the secondary electrode being connected to the power supply,

one or more movement arrangements which are designed / are the wire-guiding primary, if necessary and / or secondary electrode, and to move the support plate relative to one another in three dimensions,

a control unit for controlling the movement arrangement (s) and the power supply, wherein the main body of the wire-guiding primary electrode, a channel through which the metal wire in the solid state can be passed through to a mouth of the channel and in or directly below this mouth to a adjacent metal surface can be designed and spot or in sections welded, and wherein the metal surface is a support plate, or on a previously attached metal wire layer.

The mouth of the channel of the wire-guiding primary electrode preferably comprises a different material from the base body or consists of this, preferably a ceramic material or a different metal.

The mouth of the channel of the wire-guiding primary electrode may comprise an annular contact surface and be configured to transmit at least a portion of the current from the wire-guiding primary electrode to the metal wire.

The device further advantageously comprises a wire leading primary electrode upstream, the second electrode which is designed by conducting a second Power (shock) it to preheat the metal wire, wherein preferably the second electrode is disposed within the main body of the wire-guiding primary electrode.

It can also be provided a motorized feed is designed to guide the metal wire through the channel, preferably by adhesion via rollers to support.

The apparatus may further comprise rollers preceding the wire-guiding primary electrode which are adapted to change the cross-section of the metal wire prior to its insertion into the wire-carrying primary electrode.

The moving unit is preferably designed to move either only the wire-guiding primary electrode, or only the support plate, or both.

As already mentioned above, the opposite electric pole of the secondary electrode, the support plate or another on the object of metal can be placed opposite polarity secondary electrode.

In a further embodiment of the device, an adjacently mounted grinding surface is provided which is suitable to regrind the mouth of the wire-guiding primary electrode or possibly the tip of the secondary electrode.

Particularly preferred is further arranged in the device, a movably arranged metal-removing tool, advantageously a movably arranged grinding surface or a movably arranged cutter, which is suitable for additional shaping of the metal object during and / or after its completion and can be used if necessary ,

An inventive device, herein in analogy to the known plastic FDM-3D printers, also called simply 3D printer, does not need an artificial protective atmosphere, so no protective gas, for printing with steel. Different wires made of different metals or alloys can be used to "print" with a described 3D printer. The price and geometrical dimensions of a device according to the 3D printing process described herein is only a fraction of a common model available on the market. Relatively large objects in comparison to the size of the 3D printer can be produced with the so-called 3D printing process according to the invention from metal wire.

The method, in principle, involves the process of making an object layer by layer of wire of metal in an automated process. In this case, the wire is passed through a primary electrode of a three-dimensional printer and placed on a platform (support plate) or an already created layer or part of an object and connected by electrical current in the resistance welding process. The Electrode leading the wire, the wire and the carrier plate or build platform close a circuit when the wire makes contact between the electrode and the build platform. The electrode has a channel through which the wire is passed. At the lower end of the electrode, where the wire is led out, there is a contact surface, which in principle is mostly directed parallel to the layer to be created. In the area of the mouth of the channel of the wire-guiding primary electrode, the wire makes a bend through an angle, which in the ideal case is, for example, about 90 °. The wire is then bent directly out of the mouth. The lower, preferably annular contact surface of the wire-guiding primary electrode slides over the wire and delivers surges and preferably exerts additional pressure on the wire. The electrode preferably does not rotate around itself in the manufacturing process, but only moves in the direction of the planes, for example. The wire often forms the highest electrical resistance portion in the closed circuit during welding and is heated by the flow of current therethrough and can thereby make a metallic connection at the point of contact with the metal on which it is abutting. By moving, for example, the electrode to the build platform (or vice versa), the wire is placed below the mouth of the wire-guiding primary electrode in the plane of the layer to be created. With a channel in the wire-guiding primary electrode, which is advantageously perpendicular to the plane of the layer to be created and thus the bend of the wire in the mouth of this electrode, for example, an angle of 90 °, the wire can in all directions in the plane of a layer as it were can be applied without the need for a self-rotating electrode driving the wire. In addition, the wire with the primary electrode leading the wire through a channel and directly bending it can be easily applied in any way without the wire being pinned on top of other adjacent wire paths and blocking further jobs.

After the application of a layer of cross-section, in principle, completely unchanged paths of wire with the primary electrode, preferably drive secondary electrodes the so "aufged jerky" layer of adjacent wire paths in places and edit if necessary, the wires in the resistance welding process on make stronger connections between them to generate three-dimensional objects.

During the welding process with the secondary electrodes, the wire webs can be completely melted and melt together to produce more isotropic objects. Strong connections can thus be made everywhere between the wire paths applied with the primary electrode. The wire paths of, for example, standardized round wires can flatten through the secondary electrodes are melted and flattened to a flat plane on which in turn round wires can be accurately applied to the primary electrode. By such a fusion of the wire webs together disappears the pronounced groove pattern that would otherwise be present in cross-section almost unchanged stacked wires. The shape of the sheets of wire is thus changed by the welding process with the secondary electrodes. By the printing process with the fusion of the wire paths with the secondary electrodes, it is easy to produce airtight objects other than the wire application with only the primary wire-guiding electrode. By the thus achieved fusion of the layers with each other, large tensile forces can be transmitted between the layers and each applied part of a wire.

Preferably, the electrodes are attached to a printhead. At this cooling is preferably also attached, which consists for example of cooling fins to cool the electrodes. As a matter of principle, the secondary electrodes generally use up in the welding operations and their lower contact surface can therefore be advantageously ground down step by step by sliding over a grinding surface which is fastened to the printer. This ensures a clean electrode surface at all times. The electrodes are preferably interchangeable and advantageously there are various types of electrodes that can be used.

With the method according to the invention and with a device described here, various metals and alloys can be "printed". For example, items made of steel, stainless steel or aluminum can be produced.

With the wire-guiding primary electrode, very thin wires with a diameter of e.g. 0.1 mm can be applied precisely. By simply changing the primary electrode, other wires can be printed quickly and easily and there is a large variation in the diameter of the wires that can be printed with a printer device. The primary electrode is particularly suitable for attaching the wire only slightly and applying it in a form-fitting manner.

By the optional flat melting of the wires with the secondary electrode (s) it is also possible to set the final height of a layer. The simultaneous coalescence by the secondary electrodes of the wires that will be made part of the article will result in more equality and uniformity in the structure of the articles, making them more stable and aesthetic. Welding with the secondary electrodes creates a solid bond between the material of the individual wires and between them allows. This is especially true for the connection between the inner material and the walls of the objects to be created.

The primary wire-guiding electrode may be stationary, that is to say rigidly connected to the frame of the 3D printer, or it may be movable. If the electrode is movably attached to the device, it is preferably driven by motors and sets the way back to apply the wire on the required lanes can. If the electrode is rigidly mounted, the build platform / carrier plate moves to apply the wire to the desired locations. Both the electrode and the build platform can be made as self-moving parts.

As a material for the electrodes is a hard good electrically conductive material such as forged copper or a copper alloy or an electrode of a plurality of materials, which consists for example mainly of copper and the tip with the contact surface to the wire made of tungsten. Where the copper provides better electrical and thermal conductivity properties and the harder material such as tungsten at the contact surface for a hard lower wear surface. It is good if the electrode pad has a high melting point to better withstand high heat, and a material where the wire is applied will not stick too much to the electrode when transferring current.

The controller (or control unit) of the 3D printer controls the so-called printing operation and gives the power supply the signals for current delivery. The power supply of the primary wire-guiding electrode can also be separated from the motion control and operated independently, but this usually brings disadvantages. Also, the power supply of the primary wire-guiding electrode may be controlled partly by the overall control unit of the printer via the software and partly by hand-operated regulators on the printer with which one can easily change parameters such as the current during the printing process.

A round cross-section is suitable for the channel in the wire-carrying electrode through which the metal wire, the material is passed, so that a rotation of the wire in the channel of the electrode is possible. Other cross sections are also possible. The channel must be at least as wide as the wire being used and the channel should have a smooth surface and be as straight as possible so that the wire can be moved easily. The wire coming out of it directly outside the wire-guiding electrode has a small cross section in relation to the rest of the circuit and a very high electrical resistance. Therefore, when strong electric current is conducted through the wire from the wire-carrying electrode, the wire directly under the primary electrode heats up strongly. By the resulting heat in the wire, the wire can melt locally or completely, or with the contact surface of the metal on which the wire is applied a punctiform or intermittent metallic compound received and thus connect with adjacent tracks of metal wire.

Particularly suitable is a round wire, because of its small point or line-wise contact surface facilitates the resistance welding.

The wire may also be fused at positions with the primary electrode at locations throughout the cross-section and fused with the layer to make solid connections. The force pushing the wire through the wire-carrying electrode presses the wire against the surface on which it is applied.

Thus, the resting of the wire-guiding electrode on the wire is easily possible at the location of the lower mouth of the channel of the wire-guiding electrode should be enough space in which the bending of the wire, which is necessary to lay the wire flat in the plane , can be done. In order to have enough room for the bending of the wire, the channel in the wire-carrying electrode is preferably wider than the width of the wire and in principle wide enough to allow the bend or the area at and just above the mouth of the channel is wider than the rest of the channel and shaped so that the bending of the wire can take place. It is usually important to keep the lowest width in the area of the mouth small, while ensuring that the bending of the wire can be carried out properly and reliably by means of tensile or compressive forces in order to be able to apply the wire more precisely. Therefore, a push device which presses the wire through the wire-carrying electrode is also suitable. Such a compressive force pushing the wire through the channel allows for smaller bending radii of the wire and thus more accurate application and less wear of the wire-carrying electrode because it does not have to exert lateral pressure on the wire to pull the wire out by relative movement of the electrode to the object to be created got to. In addition, the electrode does not have to rest with the lowest surface at the level of the layer to be created. In addition, there is the glow of the wire in or below the mouth of the electrode, through the heat conduction in the wire section is welded. This is mostly important for the orders of thicker wires.

The invention therefore also relates to a method which makes it possible to produce metal objects in an automated process by the layered orders of a metal wire with a wire-carrying primary electrode through which a channel passes through which the wire is passed and in or directly Below the mouth of this channel, where the wire is led out of the electrode, is bent at an angle which is approximately 90 ° in the ideal case so that it can be designed flat on a metal surface where it is applied by the current transmitted to it from the primary electrode in the resistance welding process for the most part cross-sectionally unmodified and is usually only slightly tacked. The wire is applied by the layer-wise printing with the primary wire-guiding electrode in the correct locations according to the pattern of the respective cross-section of the object to be created. Secondary electrodes continue to drive after a layer has been applied from adjacent mainly cross-sectionally unmodified wire webs, the layer automatically on, put on her in places and further weld the wire webs in the resistance welding process to make tighter connections. In this case, the secondary electrodes can melt the wire paths under their contact surface completely to a flat, flat portion of fused together wires and flattening. The contact surfaces of the secondary electrodes, after a number of welding operations, due to wear of the contact surface by pressure welding, can be automatically abraded or abraded by a tool so that the contact surface maintains a good quality for the welding operations that it must perform.

The invention also preferably relates to a device, namely a so-called 3D printer, for producing objects made of metal, wherein the device comprises at least one primary wire-carrying electrode through which a channel passes, through which a metallic wire is passed in the solid state can emerge from the mouth of the channel and after a process of bending under the lowest surface of the primary wire-guiding electrode is pressed against the surface on which it is applied and by current transfer from the wire-carrying electrode to the wire in the resistance welding process with the metal surface which the wire is applied is connected. For this purpose, the device preferably also has at least one secondary electrode, which put on the applied with the primary wire-guiding electrode webs of wire and these together with each other stronger in the resistance welding process. In this case, the mainly cross-sectionally changed already designed with the primary wire-guiding electrode on adjacent tracks wire in cross-section can be changed by the plate-melting with the secondary electrode, so that the wire loses height and with the surrounding tracks of wire and the existing metal material of the piece which the wire is piled up can be fused.

Preferably, the device can be operated with the following (replaceable) types of the electrode, or include the following further features: - With a wire-guiding primary electrode in which the lowermost surface is an annular contact surface which rests on the bent, out of the mouth of the channel of the electrode out, part of the wire and transmits most of the current from the wire-carrying electrode to the wire to weld it.

- With a wire-guiding primary electrode with a channel which is wider just above the mouth of the channel to space for the deflection of the wire in each direction in the plane as it allows to and so as to reliably apply the wire can. In this case, the electrode with the lower contact surface on a coated wire portion at the height of the uppermost surface of the layer being applied and put on slide over when the layers are applied flat and parallel to each other.

- With a wire-guiding primary electrode with lower area with annular contact surface for welding wherein the lower cross-section has an unchanged cross-section at a defined height and is removed by the wear of the contact surface of the electrode during wire application and welding.

- With a wire-guiding primary electrode with ceramic tip, which can press the wire against the surface on which this is applied.

With a wire-guiding primary electrode with a tip from another

Metal as that of the base.

- With a wire-guiding primary electrode which does not print with its bottom surface on the surface of the layer is created during printing and exerts no pressure from above the wire, but the power for welding by a freestanding piece of wire from the Channel comes out and is located between the primary electrode and the layer that is created.

- Having a wire-carrying primary electrode having an inner second electrode which can preheat the wire through the line of a second current flow therethrough.

- With motorized feed of the wire over rollers of the wire through the

Electrode pushes through and helps to bend the wire in or below the mouth of the channel.

- With an additional electrode which preheats the wire before it into the channel of the primary wire-guiding electrode by passing a current through the wire.

- With a device which rolls the wire in another form before it is introduced into the primary electrode. With secondary electrodes of a defined height on which the electrode is unintersected in cross section, so that by wearing and grinding the bottom contact surface for welding, welding can be continued under the same conditions.

During the welding process with the secondary electrodes, the complete

Melting and dissolving the wires under the secondary electrode (s).

With secondary electrodes having any shape of the lower contact surface.

With secondary electrode with raster surface.

With rolling wheel electrode as a secondary electrode.

- With subsequent resistance welding with a plurality of mutually insulated opposite polarity located therebetween secondary electrodes between which the welding current flows.

With two opposing rolling wheel electrodes as secondary electrodes for resistance welding.

With roller wheel electrode as a secondary electrode whose contact surface for

Welding is continuously or automatically reground step by step.

- With attached passive, rigidly mounted on the machine grinding surface consisting of sandpaper, a file or a grindstone or other rough material on which the electrode surface of the electrodes can be removed.

- With attached active, offset by a motor in motion

Grinding surface, milling cutter, file or other metal-removing tool.

- With several secondary electrodes which are individually linearly moved by a common stepper motor via a camshaft.

[0073] - With an attached milling head on the printhead can run off and mill the contours of a printed layer.

- Wound with the orders of solder material wires with the primary wire-guiding electrode to produce three-dimensional objects with wire with different possible cross-sections.

- Sections of the round wires are completely melted and pressed flat.

- With a mounted on the printer milling head can mill the contours of the layers. In summary, depending on the embodiment, the invention has one or more of the following advantages:

No expensive dangerous laser needed

No protective gas or artificial atmosphere necessary for various metals and alloys

- Wires can be applied adjacent to each other, which means that less support material is needed.

[0081] It is easy to place a plurality of wire-guiding electrodes next to each other on the

Printhead be attached

No rotation of the electrode is necessary

[0083] - easy change from the printing material

[0084] - several metals printable

- Low weight and small dimensions of the 3D printer in a large space

- Production of composites possible

[0087] It is easy to attach a milling cutter to further process the contours of the layers. Especially with the layers fused together by the secondary electrodes, the contours of the layers can be smoothed by milling only very little material and brought into a much more detailed form.

[0088] - no metal powder needed

- No flash arc with a bath of liquid metal into which the wire is passed and is melted.

Adjustable layer height with a wire with the secondary electrodes

- Fusion of the laterally adjacent wires together by melting, flattening and coalescing the wires with the resistance welding process

[0092] - favorable operation

[0093] - Great difference in the possible printable layer heights and thus the

Printing speed and detail accuracy, with round wires, for example, between 0.1 mm to 1 mm in diameter, with only one change of the wire leading and --auftragenden primary electrode

- Printing process with standardized round wires which are flattened and thus give a smooth surface

[0095] Heat for melting together, which first passes at the contact points, accumulates particularly quickly in the material at the contact surfaces, so that they can merge together. Thus, several layers can be applied one above the other with the wire-guiding electrode and be fused in a welding process with the secondary electrodes.

- The disappearance of the graded lines on the surfaces by the fusion of the wire webs together

It is easy to make a strong bond between the inner padding material and the outer walls of the printed articles.

Creation of a flat planar surface of the lower layer by the

Flattening and fusing the round wires previously applied so that the next layer of round wire webs with their centerlines can always be applied at the same height thereon.

Smooth surface possible by merging with the secondary electrodes

By grinding the electrodes gives a long operating time

In contrast to the rolling wheel electrode which applies the wire, with the wire-carrying primary electrode with channel the wire can be applied in any desired way in a layer that is created without the wire on other laterally adjacent wires with the center line above the the side-by-side wires are applied and welded thereto, which would hinder the wire application process and would most likely cause the rotation of the rolling wheel electrode to break because the spot weld is not directly below the axis of the rolling wheel electrode and therefore the unwanted one Welded on a laterally adjacent wire web would have to be torn to the rolling wheel electrode to apply the wire in another direction on.

- Isotropic material properties of the printed objects by the complete merge by means of the secondary electrodes. Thus, internal forces in printed objects are transmitted uniformly over large areas.

It is easy to produce hermetically sealed objects

- The disappearance of the graded lines at the edges and surfaces of the layers, by the coalescence of the layers through the secondary electrodes, at which stress concentrations can arise under mechanical stress, which reduce the stability. And so even smooth surfaces of the printed objects are the result.

[00105] - precise design of thin wires possible - The outer dimensions of the wire-carrying electrodes with channel do not differ for different thickness wires, so they can be easily replaced

- The wire is not led into a molten bath where it then melts, but is line or layer by side or superimposed to create the geometry of an object in layers and is in the resistance welding procedure ßβ on the contact surface to the surrounding wires interconnected, either with or without handling the liquid phase of the wire.

Brief description of the figures

Embodiments of the invention will now be described with reference to the accompanying figures.

Fig. 1 shows an embodiment of a 3D printer with a primary wire-guiding electrode, with three secondary electrodes, with a build platform on which an object is stacked and with a attached to the printer housing grinding surface on which the contact surface of the secondary electrodes can be ground ,

Fig. 2 shows an embodiment of a printhead in applying wire to the primary wire-carrying electrode.

[001 1 1] Fig. 3 shows an embodiment of a perpendicular channel primary lead wire electrode to the surface to which it applies a metal wire.

Fig. 4 shows an enlargement of the mouth of the channel of a primary wire-guiding electrode during the application of wire.

[001 13] Fig. 5 shows a general embodiment of a primary wire-guiding electrode.

Fig. 6 shows an embodiment of a primary wire-guiding electrode having a lower portion with a contact surface for welding the wire, which is intended to be worn down and worn away during the printing process.

Fig. 7 shows an embodiment of a primary wire-guiding electrode with an inner second electrode for preheating the wire in the channel of the electrode.

Fig. 8 shows an embodiment of a primary wire-guiding electrode which, when applying a wire, does not rest on the wire with the lowest surface and does not exert downward pressure on the wire.

FIG. 9 shows an embodiment of a primary lead-wire electrode with a ceramic tip. Fig. 10 shows an embodiment of a block in which secondary electrodes are mounted.

FIG. 11 shows an embodiment of a replaceable tip secondary electrode. FIG.

Fig. 12 shows another embodiment of a secondary electrode.

Fig. 13 shows an embodiment of a secondary electrode having a different contact material as the main part of the electrode.

Fig. 14 exemplifies the process of mounting and welding with a secondary electrode.

Fig. 15 exemplifies the process of welding with a secondary electrode in cross section.

Fig. 16 shows an example of a structure created from round in cross-section unchanged metal wires which were applied with a primary wire-guiding electrode.

Fig. 17 shows an example of a structure of metal wires fused together by the combination of the printing operation with the application of wire paths to a primary wire-guiding electrode and subsequent flat-melting with a secondary electrode.

Fig. 18 shows an embodiment four secondary bonded together

Electrodes for resistance welding with more focused heat development in the metal to be welded.

Fig. 19 shows two opposed interconnected and electrically isolated electrodes for resistance welding with more focused heat development in the metal to be welded.

Fig. 20 shows a secondary electrode with a raster-shaped contact surface.

Further details and advantages of the invention can be taken from the following detailed description of possible embodiments of the invention with reference to the accompanying figures.

Description of several embodiments of the invention

FIG. 1 shows an embodiment of an automated device, also referred to herein as a 3D printer, with the implementation of the following main components: the printhead 105 to which the primary lead-and-wire electrode 103 is attached, and the power cable 106 of the electrodes, the block 130 with the secondary electrodes 132, 133 and 109, the grinding surface 1 14, the build platform 101 with the attached to it power cable 107, and the housing 1 17 with built-in control unit and with integrated movement mechanism.

Referring to Fig. 1, an article 102, an art object, is manufactured on the build platform 101 by the layer-wise deposition of the metal wire 104, which is thus the fabrication material. The wire 104, for example a wire of stainless steel with a round cross-section, is unwound from a roll and moved by a stepping motor whose axis 1 12 drives a roll 1 10 mounted thereon between which and an opposing roll 1 1 1 the wire 104 is driven and is conveyed by the channel 302 of the primary lead-and-wire electrode 103 shown in FIG. The wire-carrying electrode 103 is screwed into the printhead 105 moving in a plane parallel to the build platform 101 and is perpendicular to the channel 302 to the build platform 101. The wire 104 will be partially within the channel or entirely outward below the mouth of the wirewound electrode channel 302 103 bent at a substantially right angle, in a very small bending radius, so that it is pressed flat against the surface of the previous layer and by means of electricity between the primary electrode 103 and the building platform 101 and the object 102, through the part of the wire 104 flows below the electrode 103, applied by resistance welding and welded. In this case, webs of wire, according to the pattern of the respective layer of the cross section of the object 102, are juxtaposed side by side for the most part with short current impulses only slightly attached. In this case, the metal wire 104 is connected pointwise or in sections only in the fixed, mostly uninterrupted, state with the metal surface resting against it. The wire webs applied with the primary wire-guiding electrode 103 are thus usually only weakly connected to one another and to the surface on which they are applied, and can easily be torn off from this surface without being torn. On the other hand, the wire can be patterned as quickly, accurately and with great certainty and with little wear on the electrode 103. Metal articles of only successive layers of coated round wire webs have lower strength and inferior mechanical properties in most directions, as compared to articles of isotropic and homogeneous structure, for example cast articles. Therefore, after a new layer has been applied to the primary electrode 103, the secondary electrodes 132, 133 and 109 housed in the metal block 130 connected to the printhead 105 can locally approach the new layer consisting of wire paths Put on their surface and transfer pressure and current to the layer around the layer step by step continue to process in the resistance welding process, thereby substantially improving the properties of the object 102. The secondary electrodes can fuse the wire webs of a layer, which are applied with the primary wire-applying electrode 103, in cross-section entirely unchanged, flatten them and allow them to fuse together to form a unitary part of the article 102 in which the secondary electrodes carry a strong local current flow guide them through. The secondary electrodes wear off during the printing process. Their contact surface is increasingly contaminated and worn with increasing number of welds and is therefore preferably automatically removed step by step by slipping on the grinding surface 1 14, so that the contact surface is as clean as possible to not affect the welding result and to allow a much longer life of the secondary electrodes, which makes it possible to produce larger objects without interruption. The next layer is applied again in the same procedure.

The mostly existing standardized wires have a round cross section, this cross section is particularly suitable for printing by means of the primary and secondary electrodes, because the wire through the circular shape of the cross section has an increased electrical resistance in the direction perpendicular to the plane on which the wire is applied flat. For this purpose, the round wire is located only with a very small area, so that the resistance welding process, the current flow and the heat generation is concentrated at the point where the wire rests, which allows the creation of a compound with relatively low current flow. In addition, the round wires already deposited can easily be melted and deformed under the secondary electrodes because of their usually higher electrical resistance compared to the rest of the circuit and much less heat transfer from the wire to the electrode and the surface on which it is made rests, because of the very small contact surface. This, in turn, causes a lot of heat to quickly build up in the wire instead of being quickly drained, in which case the necessary melting temperature would not be achieved.

By providing pauses during the printing process, the wire can be changed and, if necessary, the support material can be removed, in addition, parts can be introduced to the objects created at locations which are no longer accessible after the printing operation. In addition, it can be determined via a sensor whether there is still wire on the coil.

The build platform 101 is linearly mounted on the rails 124 and is moved up and down by the stepper motor 128 which drives a spindle. Power to the build platform 101 could also be transferred via contact on an electrically conductive rail. A display 1 19 and a knob 1 18 on the printer housing, can operate the device. The printer is connected to a power outlet.

Fig. 2: Printhead during printing - whole unit

Fig. 2 shows the part of the print head 105 of Fig. 1 with the wire 104 applying electrode 103 during the printing process of an object 205, a screw-on angle, with the wire-applying electrode 103, which moves relative to the build platform 206 and doing the wire 104 applies. The print head 105 in FIG. 1 is mounted linearly on the guide rails 122. It is driven by stepper motors 127 via pulleys 126 moving belts 125, so that the position of the print head 105 can be adjusted to the build platform 101. In Fig. 2, the roller 1 1 1 by a spring 204 which transmits a force to the Flebel 203, which in turn transmits a force on the roller 1 1 1, pressed against the wire 104. As a result, the wire 104 is also pressed against the roller 1 10. By operating the Flebels 203, the wire 104 can be inserted from the electrode 103 and run. The force of the spring 204 on the Flebel 203 could be adjustable with a set screw. The channel 302 of FIG. 3 inside the electrode 103, through which the wire 104 is passed, is substantially perpendicular to the building platform 206 and so also the wire-carrying electrode 103 in order to apply the wire 104 in all directions as it can. At the mouth of channel 302, or shortly below, under the electrode 103, the wire 104 is bent over, as here, by the angle of typically 90 ° so that it can be applied parallel to a layer and parallel to the surface of the build platform 206. The construction platform is connected to the power cable 207 opposite to the wire-guiding electrode 103.

The rollers are arranged so that the wire driven between them is led directly into the channel 302 of the wire-guiding electrode 103. Therefore, the upper part 303 of FIG. 3, the wire-guiding electrode 103 is advantageously tapered and conically shaped. By changing the electrode 103 to print with another wire, the distance between the channel and the rollers is also properly adjusted. The wire could also be passed into a thin channel and tapered tip portion which would be mounted between the wire-guiding electrode and the rollers, with any shape of the upper portion of the electrode 103.

The electrode 202 connected to the power cable 131 is an optional complement to the printhead 105 for preheating or preheating the wire 104 by passing a precisely adjustable current set by the system controller directs the wire 104. The electrical opposite pole to the electrode 202 may be, for example, the build platform 206, the rollers 110 and 11 or the wire-carrying electrode 103. By preheating the wire 104, it becomes more ductile, less rigid, and may be softened, thereby making the wire more easily bent and the mechanical stress on the surface of the wire-applying electrode 103 is lower. In addition, the electrical resistance of the metal wire 104 is higher with higher temperature, which has a positive effect on the welding process. Similarly, the wire between the rollers 1 10 and 1 11 could be rolled to achieve a different cross section of the wire. In addition, additional rollers may be provided to allow the wire 104 to be pulled apart or rolled so that it becomes thinner. The pressure on the wire 104 between the rollers could also be controlled by an attached motor to cause the wire to change its cross-section during printing with the wire-carrying electrode 103, for example to change the layer height, or to make layers of the wire 104 in places adapted to produce a rectangular cross-section which is not melted with the secondary electrodes in order to make the surface of the first layers freestanding, supported by support material sections cleaner and more easily separable from the lower support layer. With the use of the electrode 202, a wire-carrying electrode 103 may be used whose channel is coated with a flow and heat-insulating ceramic or glass layer. By annealing the wire tensions can be solved because of the winding of the wire on the coil, so the wire can be applied more easily.

Due to the small size and complexity of the wire-carrying electrode 103, it is very easy to grow several such electrodes on a print head with wire feed mechanism, so you can print with several different wires in a printing process, for example, to print faster in the places to be able to where the precision is not so important and instead can be filled with a thicker wire.

Fig. 2 Description of the printhead parts

The wire-carrying electrode 103 is screwed into the metal block of the print head 105, which is made of aluminum, for example, and can well dissipate the heat in the electrode 103 formed in the welds from the electrode 103 and the current for welding the attached to the print head 105 power cable 106 into the wire-carrying electrode 103 well conducts. The metal block of the printhead 105 which conducts current to the electrode 103 should be electrically isolated from the guide rails, for example by a layer of plastic between the linear bearings mounted on the printhead 105 in the holes 201 and supporting it on the guide rails 122. The power cable 106 is bolted to the movable printhead 105. The insulated power cable 106 is advantageously made of many individual thin wires so that it has a great deal of flexibility and comes in a long arc coming from the power supply unit, which is installed in the printer housing 1 17, to the print head 105 so that it easily in the direction of the plane in the he can move back and forth. The guide tube 120 through which the metal wire 104 is guided from a spool to the printhead 105 is made of flexible plastic, for example, and extends in an arc from the print head 105 to an attachment to the printer housing 1 17. The guide tube 120 performs the function especially with thin wires of, for example, 0.2 mm, the wire can not get tangled and is not kinked by the movements of the printhead 105 or is exposed and dragged behind the printhead, thus hindering the printing process. In addition, the wire is so isolated. The printhead 105 preferably also cooling fins 1 13 are mounted which ensure that absorbed heat from the printhead 105 can be released quickly to the ambient air and the printhead and thus also screwed to it the wire-carrying electrode 103 is cooled. The cooling of the wire-guiding electrode 103 increases its life. For improved cooling, a fan 121 allows the air to flow to the cooling fins. The stepper motor which drives the roller 1 10 is preferably screwed to the print head 105 and moves with it.

The tip of the primary wire-applying electrode 103, with which the electrode 103 makes the lowest contact with the wire 104 and with which it transfers the welding current to it, may be made of a different metal, for example tungsten or stainless steel for printing with a wire of aluminum. In addition, between the tip of the other material and the overlying main material there may be a heat-insulating layer with small current-carrying contacts which conduct the current from the upper bulk material into the tip, so that the tip of the wire-carrying electrode 103 becomes very hot and when fresh on the lead bent wire piece during the welding process with the contact surface transfers heat to the wire and not or much less derived from this, which supports the welding process.

[00144] Apply wire

Suitable materials for the electrodes are copper alloys, which bring about the conductive properties of copper with a promoted tardability and strength, for example copper alloy with zirconium, beryllium or tungsten.

When orders of the wire, which here has a round cross-section, but could also have a different shaped cross-section, transmits the wire-leading Electrode 103 Current through the part of the wire 104 which emerges from the channel of the electrode 103 and usually has the largest electrical resistance in the circuit. Thus, the wire 104 is resistance welded together with the surface of the previous layer of the object 205 to which the wire is applied and fixed by fusing in spots or in sections because of the strong heat generated by the flow of current in the wire 104 Metallic connection is received at the point where the surface of the wire 104 contacts the metal surface on which the wire 104 rests or bears laterally and which dissipates the current. This may be the surface of the already created object 205, the build platform 206 or a metal surface on which a structure of wire is to be applied. When welding, the wire can melt in places over the entire cross section and fuse with the surrounding wires. In general, the cross-section of the wire 104 is not substantially changed and the wire 104 is only tacked on laying and adhering to the primary wire-guiding electrode 103, so that the electrode 103 is less loaded and stronger connections thereafter are made, if necessary, with secondary electrodes. The wire is bent during the orders in the form of the wire paths, which then pretend side by side the shape of the layer. The wire 104 can be applied by the wire-carrying electrode 103 over a large area without interruption. In this case, the resulting applied wire sections can abut directly against each other and they can be applied adjacent to each other regardless of the direction in which a wire section points to the wire section to which it is applied and partially welded, without the wire applied to the above directly adjacent wire part above rests and without cutting through the wire with subsequent re-placement during the printing process with the primary electrode 103. This is a great advantage over the methods that apply the wire directly by means of a rolling wheel electrode.

[00147] Voltage - opposite pole

The power comes from the housed in the housing 1 17 welding power supply and is transmitted through the thick power cable 106 in the block of the print head 105, which passes the power to the screwed in it wire-applying electrode 103, which then passes the current through the part of the wire 104 which has left directly the mouth of the channel of the electrode. This part of the wire, which is thereby highly heated, can thereby produce the connections to the metal surface which is produced by the object 205 or the building platform 206 on which the wire 104 is applied. The current then flows through the wire 104 through the already created part of the object 205 on the he is applied and the build platform 206, on which the object 205 rests and is pinned through. Then, the current flows into the power cable 107 attached to the build platform 206, which in turn returns to the welding power supply and thus closes the circuit. The wire-carrying electrode 103 forms the electrical opposite pole to the building platform 206 and the part of the object 205 applied thereon with the support material. The current flow may be bidirectional and may be DC or AC. The electrical voltage between the wire-guiding electrode 103 and the building platform 206 is very small and harmless to humans.

The welding power supply may consist of a simple transformer with electronic control, of low voltage capacitors or of high voltage capacitors with electronic control, which conduct electricity through a transformer to reach very high currents of several thousand amperes in the output. This is useful for producing extremely high, short power to create pulsed, stronger, and faster welds. Pulsed welding is important for lower resistivity metal wires and results in shorter layup times of the secondary electrodes with less heat transfer, causing the secondary electrodes to overheat less rapidly.

[00150] The beginning

At the beginning of the printing process of an object on the build platform 206, the first layer of the object is applied directly to the surface of the build platform 206. In order to be able to easily detach the object 205 from the build platform, the wire tracks of the first layer are only tacked with less intense current surges and are not fused by the secondary electrodes to the surface of the build platform 206. Thus, during the printing process, the object is fixed stably enough so that it does not become detached, and thus the lower layer does not bend or bulge due to tensions in the part of the object created thereupon, which may arise as the metal cools after the welding operations. Between the build platform 206 and the first layer of the object 205, a contact layer of adjacent wire paths can be created which has a larger area than the first layer of the object 205 or the first layer of the object 205 can be applied directly to the build platform 206 with additional Wire webs abutting the edges of the contours of the first layer. This establishes a stronger connection to the build platform 206. The object 205 is thus only weakly connected to the build platform 206, so that it can be removed easily without damaging it, for example, by pushing a thin spatula under the first layer and trying to lift the object from the build platform 206. The build platform 206 may consist of a thick reinforced aluminum sheet, can be placed on the thinner removable panels 129 and clamped or screwed, on which then the objects to be printed are printed.

[00153] Machine code

In general, the wire 104 is connected by means of current pulses from the electrode 103 to the metal surface on which it is applied. These current pulses, with a duration of usually a few milliseconds and up to several hundred amperes, are controlled by the system controller, which accesses a stored machine code, which specifies the printing operation of one or more objects. Multiple objects can be created side by side in one printing process. The machine code is e.g. a file created by a layering software that uses as input a three-dimensional CAD file of the three-dimensional object to be printed and determines therefrom the required movements of the parts in conjunction of the printhead 105 and the build platform 206 with the timed stream pulses Consequence of respective layers corresponding to the cross-section of an object, which are possible or necessary by the application and welding of wire to print a three-dimensional object.

FIG. 2: Printhead, printing

The wire-carrying electrode 103 is interchangeable and there are various types of the wire-guiding electrodes 103 that are suitable for printing differently and with different materials. Fig. 2 shows the operation of the print head 105, in which the wire 104 in layers according to the pattern suitable for the cross section of an object 205, a screw-on angle, is applied. In order that the wire is not pulled by the movement of the print head 105 relative to the build platform 206 through the wire-carrying electrode 103, the wire 10 and 11, the wire through the electrode 103 at the appropriate speed with which the wire 104 is applied pushed. The rollers 1 10 and 1 11, can be made of steel, have a smooth surface and they move the wire through the existing between them traction. This has the advantage that the engine speed can be set slightly higher than it actually has to be to apply the wire on a web. Thus, the rollers slip a little over the smooth surface of the wire 104, thereby ensuring that the wire is always pushed through the electrode 103. For this, the motor force on the wire 104 must be sufficient to overcome the frictional friction between the rollers 1 10 and the wire 104, so that the motor 208, the roller 1 10th drives, not blocked. Likewise, the spring force on the roller 1 1 1 will be advantageously chosen so that the static friction between roller 1 10 and wire 104 is neither too big nor too small. If it is too small, insufficient force can be transmitted from the rollers to the wire 104 so that it receives the necessary power from the stepper motor 208 on the roller 110 around the wire 104 in or below the mouth of the channel of the electrode 103 to bend the wire 104 parallel to the layer is created to lay.

[00157] Electrode - force - tension - pressure

By forcing the wire 104 through the electrode 103, the wear of the wire-carrying electrode 103 is reduced because otherwise the wire would be pulled through the electrode 103 causing more pressure on the inside of the channel in the mouth of the channel wire guiding electrode 103 and thus could cut into the material of the electrode 103, if it is made of a material such as copper with low hardness. In addition, it allows firmer welds through the wire-bonding electrode 103, because there are no or less tensile forces in the wire part between the wire-applying electrode 103 and the object 205, which can tear the wire 104 at stronger surges, which are necessary to make tighter connections to the Place where the wire heats up strongly and thus weakens during welding. However, it may also be printed with a non-advancing lead wire electrode 103, which wire is pulled toward the build platform 206 by the relative movement of the wire leading electrode 103, but which makes printing more difficult to control to successfully produce objects and requires more power Printhead 105 to move. In addition, pressing the wire 104 through the wire-carrying electrode 103 can more easily achieve greater precision. Stronger connections, for example, by spot-welding the applied wires, can also be performed with the wire-guiding electrode 103 when printing without pushing the wire, with the lower surface of the wire-guiding electrode 103 resting on the upper surface of the wire paths created in the layer will lie and with the interruption of the relative movement of the wire applying electrode 103 to the build platform 206 during the process of resistance welding.

[00159] Electrode - force - space - centerline radius scheme

In Fig. 5, the wire-carrying electrode 103 is shown individually. Fig. 3 shows a section along the channel 302 of the wire-carrying electrode 103 when applying a wire. Through the channel 302, which passes through the electrode 103, the wire 301 is passed until it comes out in the funnel portion 401 of the channel 302 shown in FIG. 5 - the part of the mouth of the channel 302. Fig. 4 shows a enlarged illustration of the area of the section of the wire-carrying electrode 103 with the bent in the mouth of the channel portion of the wire with its radius of the center line R. The center line radius R is always greater than the radius of the wire, for a wire with a circular circular cross-section. The smaller the centerline radius, the easier it is to apply the wire precisely, because the bent portion of the wire 301 between the wire-guiding electrode 103 and the metal surface 403 at a smaller centerline radius is closer to the central axis of the electrode 103, the axis of the channel, than the reference applies to the orders of the wire when driving the predetermined paths on which the wire 301 is to be applied. This is especially true when re-putting the wire-carrying electrode 103 to start with the orders of a new web from the wire. But the smaller the center line radius R, the larger must be the force F acting on top of the wire 301, which moves the wire through the electrode 103 and ensures the bending of the wire 301, this being true to the smallest possible center line radius to be printed can.

The path traveled by the wire-carrying electrode 103 should be programmed so that the design of the wire under the annular surface of the electrode 103 is on the correct tracks to make the layer more faithful. If the electrode 103 moves only with the main axis, that of the channel 302, the tracks on which the wire should be located afterwards, then the wire from the wire-guiding electrode 103 is not always applied to the correct tracks, because the mouth of the channel in which the wire can reverberate when orders are wider than the wire, then the wire is applied to more rounded corners and shorter curves than the descends the main axis.

FIG. 4: The channel 302 has a circular cross section and the diameter d which is slightly larger than the diameter q of the wire, for a wire of circular circular cross section and which is slightly larger than the widest point of the cross section of a wire having a different shaped cross section , For example, a flattened wire, which had a round cross-section before a rolling process and subsequently has a rectangular-shaped cross-section.

[00163] Electrode - force - rounding - room - scheme

Much heat is transmitted from the welding point through the wire into the part of the wire which, because of the small centerline radius R and because of the small distance D, is very close to the welding point and bent in the mouth of the channel of the wire-guiding and wire-applying ones Electrode 103. This can significantly reduce the stiffness of the wire, thus ensuring that a wire-carrying electrode 103 can be set to a very small bend radius and centerline radius R around the wire 301 easily and precisely.

FIG. 5: The contact surface 402 with which the wire-carrying electrode 103 rests on the upper surface of the wire webs of the layer that is being created is located in a continuous annular manner around the mouth of the channel 302 and is in parallel printing position over the build platform 206, FIG. so that the wire can be applied in all directions of the plane, as it were, without rotation of the electrode 103 around itself. When the electrode 103 rests on the build platform 206, it contacts it on an annular surface. The wire-carrying electrode 103 exerts a pressure on the bent wire on which it rests and presses the wire 104 against the surface on which the wire is applied, so that the welded connections are made as directly as possible on the newly bent part. The bending of the wire 104, as in this case, the perpendicular electrode 103 to the surface of the layer is created with a perpendicular to this channel 302 of the wire-carrying electrode 103, for example, the angle of 90 ° takes place in the end of the channel 302, in the closing area to the mouth of the channel is wider by the rounding 401. This funnel-shaped rounding 401 provides sufficient space in the interior of the electrode 103 so that the wire can be bent directly by an angle, for example of 90 ° and the contact surface for welding 402 of the electrode 103 can rest on the bent wire. The annular contact surface 402 resting on the bent portion of the wire 301 and applying pressure to the wire generally conducts most of the current through the wire 301 so that it can be welded well in the portion below the location where the contact surface rests and has, for example, a width corresponding to the diameter of the wire 301 and an inner diameter D which is between twice and four times the diameter of the round wire 301. The contact surface 402 slides over the surface of the applied wires and is only on very low, minimal pressure on the wire in the general printing process, so that it is less stressed and does not wear too quickly. In addition, a width b of the ring of the annular contact surface lying 402, which is preferably not greater than the width of the wire and an inner diameter D which is preferably not greater than twice the diameter of the wire, for a wire with a round cross section so that the Electrode rests on as few adjacent wire paths as possible and unnecessarily transfers power to them. In addition, when the width b is set too large, it is not ensured that enough current for welding is passed through the part of the wire currently being conveyed out of the channel 302 of the electrode 103. However, the wire-carrying electrode 103 may also apply wire without resting on the wire 402 on the wire, where less severe surges are passed through the free-standing portion of the wire between electrode 103 and the surface on which the wire is being applied.

In order to make stronger connections in a continuous moving printing operation of the wire-guiding electrode 103, the positive force F acting on the wire 301 from above, the wire 301 passing through the channel 302 of the electrode 103 should be large enough for the wire 301 to move Wire on a smooth flat metal surface with no connections to this, with the positive force S in another, rotated in this case an angle of 90 ° direction, can be pushed with the low pressure electrode, with its contact surface 402 on the bent wire section. Where the wire is nothing in the way. The circular outer edge of the current transmitting annular bottom contact surface 402 is configured by the fillet 404 to allow the electrode 103 to more easily slide over bumps, such as small pieces of wire protruding out of the layer that have not been cleanly applied, rather than tangling or applied structures to damage. For this purpose, a slightly spring-acting suspension of the wire-guiding electrode 103 or the building platform 206 is also suitable.

Fig. 5 shows the thread 502 and the nut-shaped portion 501 with the wire-carrying electrode 103 is screwed into the print head 105. However, a wire-carrying electrode 103 can also be attached differently to the print head, for example by a plug connection.

[00169] separating

Fig. 2: Through the rollers 1 10 and 11 1, the wire can also be transported backwards through the wire-carrying electrode to support, for example, the separation of the wire. To separate the wire below the wire-carrying electrode 103, the electrode 103 can be a stronger current pulse on the coming out of the electrode 103 and directly bent below the contact surface of the electrode 103 located piece of wire with simultaneous backward thrust of the motor 208 with the roller 1 10 transmitted. Or the wire is severed with a current pulse with the simultaneous or subsequent movement of the electrode 103 from the point where it rests on the piece of wire, for example, by a small movement of the electrode 103 upwards, away from the layer. During separation, the part of the wire which has already been attached between the channel of the electrode 103 and the flat part of the layer is heated by a short current pulse to such an extent that it melts or becomes very hot and is torn by tensile forces exerted on the wire becomes. This process should be set so that no or as little as possible sparks or flashes of light, otherwise contamination by oxidation or air bubbles can occur on the wire. Due to the possibility of sparks, flashes of light or metal spatter, the space should be sealed from the environment, however, it does not have to be airtight for the use of metals that do not ignite in the air during printing and release any pollutants. Through a door one then gains access to the interior of the printer. On the housing 1 17 windows can be mounted through which one can observe the printing process.

Objects with free-standing sections can be created in the support material is applied below them layer by layer. The support material abuts against the lower surfaces of an object and consists of metallic wire which has been applied to the primary electrode and has also been post-processed with the secondary electrodes. Thus, on the current-conducting support material wire may be pinned to the object that is to be created. The first layers of freestanding parts of an article to be created, which are applied to layers of support material, are subjected to less intensive welding operations, but the farther they are from the layers of support material, the stronger the welding operations are performed to allow the support material to pass through easily remove subsequent tearing off. The support material usually consists of the same wire as the object being created. However, it can also be in the printing process with another variant of the 3D printer of FIG. 1 made of a different material, which is applied with a second attached to the print head 105 primary wire-applying electrode. For example, the aluminum wire support material for an article may be made of steel, or vice versa, so that the wire paths of the first layer on the support material may be fused together by the secondary electrodes without the support material forming too strong a connection. The support material can then also be made of two different wires. With a 3D printer from FIG. 1 with two wire-applying electrodes composites can also be created by the alternation of the material of the adjacent wire paths of a layer. The support material made of metal is also necessary for power conduction.

The use of different electrodes is generally dependent on the geometry and the material of the wire, as well as the printing process with the final result to be achieved.

The channel of a wire-carrying and -auftragendem electrode must be large enough in principle, so that the wire once within the channel about its own axis can be rotated so that the wire can be laid in a single plane in all directions without cutting through the wire. In addition, the channel of the electrode should not be so wide that the wire forms a spiral-like shape in the channel or kinked by the push conveyance and so could block the printing process.

The wire-carrying electrode 103 may be mounted in a resilient suspension and / or the build platform 101 may be resiliently mounted, so that the pressure with which the wire-carrying electrode 103 rests when applying the wire, by the positioning of the electrode 103 to the build platform 101, can be easily controlled, so that the pressure in small position deviations not too large and the wire-applying electrode is not damaged.

[00175] Worn-out wire-guiding electrode

Fig. 6 shows the wire-carrying electrode 601 when applying wire 606 on a metal piece 607 with a section in the region of the mouth of the channel 605. It has a nut-shaped portion 602 with which it can be screwed into the print head 105. Below this subregion, it passes into the intermediate part 603, which tapers in the end region 604 of the electrode 601. The channel 605, which preferably passes right through the electrode 601, is wider than the wire 606 which is passed through this channel. The channel 605 provides sufficient space for the deflection of the wire 606 in the lowermost part, just above the mouth, of the channel 605. This allows the electrode 601 to rest directly on the bent portion of the wire lying flat on the layer to which it is applied. The lower part 604 of the electrode 601 is an area intended to be worn during the printing operation. Therefore, if the region 604 has a new flaw T when the electrode 601 is not changed, the lower annular contact surface 608 which is worn by the wire welding, with which the electrode 601 rests on the wire, may degrade during printing without impairing the function and the effect of the electrode. By applying wire in all different directions in one plane, the contact surface of the electrode 601 is uniformly worn. The lower part of the electrode may also be ground automatically by the printer by moving the electrode 601 back and forth on the contact surface on the grinding surface 14. It is also conceivable a printer in which the electrode anfährt a cutter or grindstone to be worked up so that the quality of the welds does not deteriorate. This primary electrode 601 is particularly suitable for applying wires which are intended to be directly fixed together, for example for printing without the use of secondary electrodes. In addition, it is suitable for applying wires with a rectangle-like cross-section, the thicker ones Electricity or stronger, longer lasting current pulses need to make a connection, because the wire-carrying electrode 601 is much more stressed and the lower contact surface wears quickly. The electrode 601 can be charged much more. By the pressure exerted by the wire 606 on the electrode 601 in the lowermost region of the channel 605, the lowermost edge of the channel 605 receives the rounding 609 which results when the wire 606 is imprinted.

Double electrode

7 shows a section of a wire-carrying electrode 703, which consists of two electrically insulated electrodes, another variant of the wire-carrying electrode 103. Through the inner tubular electrode 702, the wire

701 headed. Between the upper, inner electrode 702 and the wire-applying electrode 703 is an electrically insulating layer 704, which is heat-resistant, for example made of a ceramic material or of a heat-resistant plastic such as Teflon. The electrode 703 terminates above the lower contact surface of the electrode 703 with which the welds are made. The inner electrode

702 serves to preheat the wire by passing current through the wire in the electrode 705. The electrical opposite pole of the electrode 703 may be either the lower wire layer 706, the build platform on which the wire 701 is applied, or the lower electrode 705. By preheating or preheating the wire 701, it becomes more ductile, loses rigidity and is more easily bent, and the electrical resistance of the metal wire increases with increasing temperature, which in turn aids in the process of welding to the contact electrode 705. In addition, the entire electrode 703 may be designed so as to be able to produce firmer connections in the continuous printing process without pushing the wire through the electrode 703 and with the design of the wire 701 from the electrode 703 by pulling the wire through, in which the electrode 703 Wire 701 adheres only with weaker current pulses and the electrode 705 can then perform the stronger welds without causing the wire is cut, because between the part of the wire to which the welded connection is created and the wire-brushing electrode 703, a piece of wire is present is attached to the layer 706 and this can forward the tensile forces to the layer 706, without causing the coming out of the electrode 702 wire 701 is severed. In this embodiment, the electrode 705 has a lower partial section which can wear without the contour shape of the contact surface changing, that is to say the cross section of the lowermost partial section remains unchanged over a certain height. This form is particularly suitable for thicker wires (0.4-1 mm) which are characterized by the reduction of the Flex the stiffness with lower force to smaller bending radii due to the higher temperature. The electrode 703, after mounting on the printhead of the printer, makes electrical contact with an extra power cable, thinner than the cable 106, which carries current from the welding power supply and is driven by the controller.

[00179] Non-bottom electrode

Fig. 8 shows a wire-carrying electrode 801 which does not rest with the lowest surface on the surface of the layer created during the printing process. The channel inside the electrode 801, through which the wire 802 is routed, need only be shaped so wide that the wire can be easily passed. The wire is bent underneath the bottom surface of the electrode 801 so that it can be laid flat in the plane of the layer to be created. By current pulses which are passed through the wire, the wire on the lower structure 803 is pressed on this and rests attached. These current pulses heat the wire 802 in the freestanding portion between the end of the channel of the electrode 801 and the surface of the structure 803 on which the wire 802 is applied and make it very ductile so that it can be easily shaped. The printing process with the electrode 801 which does not rest on the layer being made is very gentle to the wire-applying electrode 801. Suitable for thicker wires and wires coated with solder material in which the inner main wire does not melt and during printing for the accurate shaping of the structure to be created, while the solder material melts around the wire 802, by the heat generated by the current in the portion of the wire between the electrode and the surface on which the wire 802 is applied, and at the small contact point to the below or next to it already applied wire web can melt with the existing solder material there and so fills gaps between the wire webs, when the structures on which the wire is applied are thin enough so that they are hot enough. Wires may be clad with brazing to make air and water proof surfaces, and stronger connections between the wire paths easier, using only the wire-carrying electrode and avoiding excessive wear of this electrode. When melting the solder around the wire, a large part of the solder material always sticks to the wire so that it is applied with the wire. An advantage of the wire application process with this non-overlying electrode 801 is that it ensures that the current is transmitted integrally through the portion of the wire 802 leaving the channel of the electrode 801, and thus the welds are made thereto only. It allows the application of wire with little or no wear of the wire-carrying electrode. Disadvantage over the other wire-guiding and applying electrodes is that when separating the wire a small piece of wire can protrude from the layer, which can interfere with the subsequent printing process. In addition, there may be problems with the separation, as well as more oxidation on the wire and less pressure on the lower resting part of the wire, which in turn, for example, when starting to apply a new wire section to detach the tip of the wire, by a by the different fast page-dependent cooling and Thus, caused by contraction of the wire caused crimping of the wire.

[00182] Ceramic electrode

Shown in FIG. 9 is the electrode 902 which applies the wire 901 to a metal part 904. The electrode 902 differs substantially from the electrode 103 of FIG. 5 and FIG. 3 in that the lower part, the tip with which it rests on the fleas of the upper surface of the layer to be applied, consists of a non-electrically conductive, hard and nonconductive material 903, preferably a ceramic. It is basically suitable for thicker wires depending on the material.

In addition, a contact of sheet metal, or brushes, for example, small wires of copper, may be mounted inside the channel of the electrode 902 and press against the wire 901, especially at the end of the channel to ensure that the current passes over a larger, better defined surface is transferred to the wire 901 and thus can provide more constant conditions and welds. In general, since there must be a tolerance between the channel of the wire-carrying electrode 902 and the wire 901 for the wire to move, this generally causes the wire 901 to make electrical contact on a very small area alternating during the printing process Electrode 902 has. This may cause the welds to be less constant because of the amount of current flowing through the alternate length of the wire member and the variable resistance of the wire member.

The electrode 902 ensures that the current is transmitted entirely through the wire and thus the welds are performed only on this wire 901.

The electrode 902 absorbs the lateral pressure exerted by the wire 901 at the end of the channel and, during separation, can lay flatly protruding pieces of wire flat against the lower layer during flinching.

The ceramic tip 903 may be attached, glued or screwed to the electrode 902 with a press fit.

[00188] Abrasive surface Fig. 1: On the printer housing 1 17, a bar 1 16 is mounted on a Abschleiffläche 1 14 is mounted parallel to the building platform by means of a clamp 1 15. For example, the abrading surface 114 may be a piece of sandpaper that can be easily replaced, or even a grindstone or a file. The lower surface of the secondary electrodes wears off during the printing process. Therefore, after a certain degree of wear, it can be sanded off advantageously on the grinding surface 14, so that the lowest contact surface is again suitable for performing welds. Several attached grinding surfaces of different roughness are also possible. A brush may be mounted on the printhead 105, sweeping away the particles removed from the electrode on the grinding surface 14, or a fan doing this with an air jet. A motor driven, moving abrasive surface on which the electrodes can be approached, for example a rotating abrasive surface, is also feasible to machine the electrode surface.

[00190] Secondary Electrode Block

Block 130 includes the secondary electrodes. It is attached to the movable printhead 105 in FIG. 1 and is shown in more detail in FIG. The secondary electrodes 132, 133 and 109 are linearly movably installed in the block 130. As a material for the electrode block 130, a good flow and heat conductive material such as copper or aluminum is suitable. In the interior of the block 130, for example, a camshaft 1003 is introduced which is driven by a stepper motor 1001 which is connected to the block 130 by an insulating connector 1010. As the camshaft 1003 rotates, depending on the position of the shaft, the secondary electrodes 132, 133 and 109 move up and down. The cams of the camshaft 1003 are here offset by an angle of 120 ° about the axis of the shaft. Thus, with only one stepping motor, a plurality of secondary, here three, electrodes can be controlled individually, so that they can be put on individually and perform a resistance welding process. The current for welding with the secondary electrodes is conducted from the welding power supply via the power cable 106 of FIG. 1 via a connecting part 123 to the metal block 130 and via contact in the secondary electrodes. The electrical opposite pole to the secondary electrodes is the build platform 101, from which the current through the power cable 107 leads back into the welding power supply, where then closes the circuit for welding. In this implementation, three secondary electrodes are built in to print faster and to extend the life of the printer without renewing the secondary electrodes. On the secondary electrodes 132, 133 and 109 are compression springs 1005 with a Locking ring 1004 attached. The compression springs 1005 push the electrodes into the block 130 and against the surface of the cams of the camshaft 1003. With the cam 1003 of the camshaft 1003, for example, the electrode 132 can be moved deeper than the other electrodes so as to be ground individually by slipping on the grinding surface 14 can be placed individually on a layer of applied with a primary electrode 103 wire webs to melt them and to weld. The stepper motor 1001 could drive the camshaft via a transmission, for example, via a self-locking worm gear to boost the force of the cams on the electrodes. A pressure sensor may be attached to the printhead 105 to measure the force with which the electrodes are placed to be considered as a size in the printing process. For this, the machine can determine whether the electrode touches down by the electrical contact of the secondary electrodes with a layer of an object or the build platform. This also applies to the primary electrode 103. Due to the rectangular shape of the electrodes, they can be placed several times on a layer and cover all areas without having to put them in the same place several times. The secondary electrodes heat up strongly during the welding process and therefore have to be cooled. Therefore, a large radiator 1008 with cooling fins is preferably attached to block 130 which is cooled by fan 1009.

Smaller electrode pads are suitable for thin spots where you do not want to heat too much or the already with the primary electrode applied wire paths are close together. The larger ones are intended to weld places where little material has been applied, for example, the inner space of objects that are printed with little fill, that is, filling the interior of the items with a lattice-like structure with a lot of void space.

Other types of secondary electrodes

Fig. 12 shows a secondary electrode 1201 having a lower portion in which the cross section is equal to the lower contact area everywhere, which when grinding on the grinding surface is machined out of the base of the electrode having a much larger cross section and above Area with the same cross-section as the contact surface is located. As a result, the electrode 1201 may have a higher wear-out portion with which the welds can be made without the electrode overheating during welding operations. Due to the larger cross-section, the heat is better dissipated, as well as the electrical resistance is smaller, so less heat in the electrode caused by the flow of current. Fig. 1 1 shows a secondary electrode 1 101 with exchangeable lower tip 1 102 of the Contact material. The replaceable tip 1102 is pyramid-shaped so that it has less heat. In principle, it requires different grinding surfaces, which are parallel to respective surfaces of the electrode tip 1 102 at which they can be reground.

[00195] Secondary electrode - tip

Fig. 13 shows a lower part electrode 1301, the tip of the electrode, the contact material 1302 of a metal other than the base. The adaptation of the contact material 1302 to the material, metal or alloy from which the wire is made, allows for better welding operations and may provide less adhesion of the electrode 1301 to the wire material during welding. For example, a tip made of tungsten or stainless steel, for the welds of aluminum wire. Some types of stainless steels are particularly suitable for aluminum, because they heat up strongly due to the high resistivity due to the strong flow of current during resistance welding, thereby directing the resulting flash further into the aluminum, which makes it much easier and faster to melt. Added to this is the low adhesion to the aluminum during the resistance welding process, whereby, of course, the composition of the stainless steel also matters. In addition, the flash produced in the wire during a welding process is dissipated much less rapidly into the electrode material, because the tip, for example made of stainless steel, has lower thermal conductivity than the main material of the electrode 1301, for which copper is particularly suitable. The tip 1302 can also be made of several materials, for example the lowermost part, with the contact material of tungsten, and between the main material and the tungsten, a layer of stainless steel, with a particularly high electrical resistance, which heats up strongly during welding and heat on which transmits tungsten, which, although very hot, has even more flannability than the stainless steel above would have at the temperature setting. The tip 1302 can also be abraded on the grinding surfaces. In the main material of the electrode 1301, above the tip 1302, holes are formed through which air can circulate and increase the surface so that the bulk material of the electrode 1301 is better cooled and the thermal conductivity between the hot tip 1302 and the main material is lower the electrode block receives less heat. The transition between the tip 1302 and the bulk material of the electrode 1301 is realized in a small area so that the heat flow between both materials is less.

[00197] Secondary Electrodes - Printing Process

The principle of the welding process with the secondary electrodes of the printer of Fig. 1 is shown in Fig. 14. After a new shift, after printing is occupied with the wire-carrying electrode 103 on the metal part 1404, with only slightly connected to the lower surface lying wire webs, set the secondary electrodes individually on the surface of this layer of wire webs, in which the wire web 1403 is on, exert a pressure Depending on the location and settings, they conduct a strong current through the wire paths for a certain time. They heat up so much because they represent a section in the circuit with relatively high electrical resistance, allowing them to melt, melt and melt together and with the surrounding applied material. For this purpose, a wire 104 with a round cross-section, which is applied when applying with a wire-guiding electrode 103 only by small point connections on the surface on which it is applied with a non-changing cross-section, is particularly suitable as the input material. As a result, the wire webs thus applied have a high electrical resistance in the direction of current flow perpendicular to the plane in which the wire webs lie compared to the rest of the circuit. Thus, the newly applied layer can be selectively heated at the point at which the secondary electrode 132 rests in this case. However, a wire with a rectangular or rectangular cross-section is also suitable for printing with primary and later with secondary electrodes that fuse the wire. The welding current can be AC or DC. The structure of the wire paths applied with the primary electrode 103 changes with the secondary electrodes when reflowed. The goal is to create an object with non-directional, isotropic material properties to produce stable objects. The secondary electrode 132 has a flat surface 1402 which, when housed in the block, rests in parallel against a flat surface in the block 130 so that it is not twisted in the block 130. The upper part 1401 may be narrower because it does not have to carry heat and no current, and around it a spring 1005 may also be mounted.

It is also possible to apply several layers in succession and on top of each other with the primary electrode 103, for example two or three, after which the secondary electrodes may be placed on the uppermost layer and the plurality of layers applied only to the primary electrode 103 may be applied to each other and weld the surface on which they rest. Due to the multiple stacked layers of wires, which are unchanged in cross-section and only very slightly welded, the electrical resistance of the point to be welded is higher, which favors the resistance welding process. The layers become less frequent heated, resulting in less oxidation, less wear of the secondary electrodes and less power consumption. Likewise, this can be faster.

In this case, the electrode 132 with the contact surface of the tip 1007 which is intended for the resistance welding process on a plurality of wire webs, such as the wire web 1403, set up at the same time. The cross-section of a coated and adhered web of wire 1403, seen in FIG. 15, may change completely during the welding process with the secondary electrode 132 as the wires completely dissipate and become an isotropic, homogeneous portion of the article 1404 upon cooling. By thus attaining stronger bonds between the layers, the finished articles have a large tensile strength corresponding to the metal in the direction perpendicular to the layers. In this case, the voids and gaps between the overlying webs of wire in the merger of the adjacent wires can be closed when the wires are close enough together. By melting and flattening the wires having the width h of the cross section, the final height of the layer thickness H can be adjusted, unlike the layer thickness of a layer consisting of sheets of wire which are only attached and unchanged in cross section. This makes it possible to achieve smaller layer thicknesses than the thickness of the wires. Also, different layer thicknesses can be made using the same wire, as well as within the print of an article. Thin layers are possible, for example with a 0.2 mm diameter round wire, which is flattened to a height of 0.1 mm or 0.05 mm. In Fig. 15, the height A of the lower welding intended part of the secondary electrode 132 is shown. This part is equal over the height A in cross section and thus ensures after the removal of the lowest contact layer for a constant welding result, until the height A is completely removed.

The flat surface created with the secondary electrodes allows the wire webs of the next layer to be easily applied thereon.

In addition, when printing objects that consist only of round wires that are unchanged in cross-section, using a wire-guiding and wire-applying electrode 103 results in many gaps in one plane, for example between parallel wire paths. If, when new wire paths are applied to these gaps of lower layers, the wire webs are pressed firmly against the surface of the underlying layer, this results for the new layer, measured from the uppermost surfaces of the underlying layer of round wire webs, in which the respective new ones On the gaps applied wire paths are, a lower layer thickness than the thickness of the wire at the locations over the gaps lower layer. These differences in height in the layers to the surface of the build platform 101 may add up over the layers until further printing is no longer possible and the print becomes a failure. It is important to be able to simply apply the wires so that the area of the bottom layer on which a round wire is applied without cross section is flat. The creation of a flat surface is achieved by the welding processes of the secondary electrodes.

To produce areas that must have a precise height with a tolerance. When the wire is melted and flattened after being applied to the primary electrode with the secondary electrodes, the layer height for each layer can be varied, unlike the stratification of wires which remain unchanged in cross section where the height of the sections is always a plurality is the constant height of a layer. Thus, with an average much higher layer thickness, areas of an article to be printed can be created faster, which have to comply with a certain tolerance of the height.

When printing the interior of the objects, the wire paths applied with the primary wire-guiding electrode 103 may overlap in a layer or be applied in places twice, for example, to quickly create an internal lattice structure from a continuous wire section. After the primary printing of a layer with a primary electrode, the secondary electrodes compress and fuse the applied wire webs into a uniform flat surface. In the process, the points where wire paths overlap and abut one another become fixed fused nodes. The juxtaposed wire webs are strongly interconnected by the Zusammeneinanderverschmelzen. It is therefore usually not as important as precisely the wire paths are applied next to each other, as this way any space can be filled inside.

For a defined layer thickness, the volume of wire material can be more rapidly applied by the wire-carrying electrode 103 using a thicker round wire which is thereafter melted and flattened than with a thinner round wire having the diameter of the thickness of the layer.

The electrodes could also be water cooled and have channels in the interior through which cooled water is circulated. The support material applied to the wire-carrying electrode 103 can also be reworked with the secondary electrodes.

[00207] The machine can automatically take breaks when overheating. A moving air exchange between interior and ambient air ensures cooling. The parts are ready after printing immediately.

[00209] Sanding

An oxide layer can form on the contact surface for welding, which conducts the current very poorly. The surface may become rougher, smoother and degrade due to the welds, resulting in ever poorer conditions for the quality of the welds. Therefore, and so as not to be adhered after contamination of the contact surface by welding, the contact surface for welding the secondary electrodes can be ground off automatically. A printer similar to that in Fig. 1 with an advanced mechanism for displacing the secondary electrodes in vibration and / or rotation is conceivable so that the electrodes do not adhere during welding. By grinding, the contact surface is smoothed and remains flat and even.

By the wear-away area with the lower contact surface with which the secondary electrodes transmit the current to perform the welds and the grinding of the contact surface, the life of the electrodes is considerably extended. For example, if the lower contact surface is suitable for an average of 1000 welds, the height of the lower abrasion foreseen region is 15 mm, and the electrode can be worn 25 times per millimeter to be suitable for welding, then the electrode is sufficient for 375,000 welds before it needs to be replaced. The wear of the electrode may be predicted by the number of welds, the amount of wire under the electrode at the welds, the flow of current through them, the temperature of the electrode or the time interval between welds, and the pressure with which it is applied during welding become. By way of example, a stainless steel cube 100 mm wide, with a square contact electrode for welding 5 mm wide and with a layer height of 0.2 mm, by flattening and melting a round wire of 0.4 mm is created to print, it needs at least 100 * 10 * 10 * 5 * 4 = 200000 individual welds.

[00212] pattern

FIG. 16 shows a structure 1601 made of round wires which were not changed in cross-section during and after the layered deposition. Therefore, the surface of the structure viewed from the side of the layers has a pronounced groove pattern. For example, the structure of Fig. 16 is printed using only the wire-carrying electrode 103 with weak current pulses and welds. The wires stacked on each other only touch one another linewise or pointwise. In contrast, the structure 1702 in FIG. Fig. 17 shows the result of the respective wire-applied electrode deposition 103 and fusion with the secondary electrode 132 of the respective wires of the structure 1601 with the wires surrounding the respective wires. A large part of the undesirable and disturbing step pattern or groove pattern disappears due to the process of surface minimization of the molten metal resulting from the fusion of the wires, which is caused by the surface tension of the liquid metal during the welding process. This makes the layers less visible. Due to the more uniform structure of structure 1702 thus achieved, the material properties are much less directional than those in structure 1601. Structure 1601 is much less mechanically resilient along most directions than structure 1702. In addition, the walls of structure 1702 are large in size Safety are hermetically sealed. The resulting surface of the printed articles by fusing by means of the secondary electrodes can be very smooth, which plays a very important role in mechanical engineering. Moreover, with the disappearance of the groove pattern, the stress concentrations that may otherwise result in the grooves on the surface of a printed object under mechanical stress disappear. In addition, with less layer resolution, a better, more precise surface closer to the original of the model can be created and printed faster.

Particularly important is the connection between the walls of an object and the inner material, which is so easy to create, by merging the adjacent wire paths into a continuous area. The connecting portion 1701 from the externally rounded appearing welds connections is shown in Fig. 17. These soft transitions make the objects much more stable, because the internal forces are transmitted more uniformly over wider areas or areas, in contrast to the connection between round wires, which are unchanged in cross-section, as shown in FIG. 16.

The contours or edges of a layer, which later become the surfaces of the objects to be created, can be applied with the wire-guiding electrode from longer, uninterrupted pieces of wire, which are directly thereafter connected to a secondary electrode with a larger contact surface, for example electrode 109, fused with the lower layer, so that the surface of the objects to be created smoother and level.

The layers fused together by means of the secondary electrodes give objects whose properties are very close to those of cast parts and require little post-processing.

[00217] Secondary Electrodes - Block and General Function Between stepper motor 1001 and camshaft 1003, a torsion spring 1006 is attached, which allows a secondary electrode to abut on a layer of non-decreasing pressure when the electrode is melted by the wire webs under it, with a movement of the stepper motor 1001, not must be exactly tuned sinks. The torsion spring 1006 can also be replaced by a flexible intermediate piece. The torsion spring 1006 is not mandatory. The secondary electrode 132 is the one with the smallest bottom contact area. It is suitable for merging areas which thereafter have a continuous area equal to the area of the surface of the contact area 1007 of the electrode 132. The contact surface of the secondary electrodes is preferably rectangular, so that the electrodes can cover the entire surface of a layer by multiples approach and placing the electrodes on individual partial surfaces of the layer, without causing overlapping areas exist on which the electrode with a portion of the contact surface several times.

[00219] One or more wheeled electrodes may also be attached as secondary electrodes to the printhead. On each of these a grindstone can be mounted which is pressed with a spring against the contact surface of the electrode and slowly abrades the top contact surface as soon as the rolling wheel electrode rotates. In this case, the Rollradelektrode can sit on a layer with applied wire paths, roll over them, transfer electricity to them and they weld more, and if necessary, they melt and flattening. A rolling wheel electrode can also be moved over the camshaft. In addition, a grinding surface can also be approached at their welding contact point is removed in order to achieve significantly longer operating times can.

The welding current and its flow time is adjusted to the secondary electrodes, the respective amount, thickness, shape and composition of the wire webs as well as the required final height of the layer. If a secondary electrode does not drop enough during a welding operation, then this can be felt by a pressure sensor, for example, and it can transmit more current to the location that it wants to weld.

The 3D printer apparatus may also be constructed such that one or more cutters may be mounted on the printhead 105, which after printing with the primary electrode (s), or with the primary and secondary electrodes, may recreate the contours of the new milled layer to achieve improved precision and surface finish. For example, an attached router on the printhead, which is driven by a motor, may be oriented perpendicular to the build platform 101, and so may be accurate by the printhead movement mechanism Depart ways. During the milling process, the milling cutter then only needs to mill a very small amount of material, which means that it can hold for a long time, quickly cut off the contours, and with a thicker wire to print better precision can be achieved. The mounted on the print head 105 milling head could also be made multi-axis.

Fig. 19 shows a part consisting of two opposite-pole electrodes 1901 and 1903 which are very close to each other and are electrically insulated from each other. Between the electrodes 1901 and 1903 is an insulating layer 1902 which separates the two electrodes from each other. The layer 1902 may be, for example, Teflon or a ceramic material. The two electrodes have a rectangular contact surface for welding, when placed on a metal layer, current flows between the electrodes during welding through the underlying metal which closes the circuit, causing the metal to heat up directly below the electrodes. The advantage here is that only the area of the metal to be welded located directly under and between the electrodes is heated so that more heat can accumulate more quickly and precisely so that the welding is improved. The lower contact area of the electrodes can wear down and be ground down over a certain fleas, so that the electrodes last long. One of the electrodes 1901 and 1903 could also be mounted on the opposite electrode so that it can move towards it and be pressed by a spring in the resistance welding process against the surface at which the welds are made so that both electrodes are always in contact with that surface to have. To ensure that both electrodes 1901 and 1903 are always in contact with the material to be welded during resistance welding, the electrodes can be moved back and forth over the surface on which the welds are made until both electrodes have electrical contact, say, for example to ascertain that the determined electrical resistance between the electrodes approaches zero.

FIG. 18 shows a part consisting of a plurality of electrodes 1801, 1802,

1805 and 1806. The electrodes 1802 and 1805 are separated from each other and insulated from the electrodes 1801 and 1806 by the insulating layer 1803. The principle is the same as in the part of Fig. 19. However, in the part having the two rectangular electrodes of Fig. 19, two parts are generally required to be seen as shown in Fig. 19, preferably rotated by 90 ° from each other mounted on the printer to weld any underlying structures equally. The electrodes 1801, 1802, 1805 and

1806 together result in a part that can be moved in a block and via which the welding current is transmitted to the respective electrodes via mutually insulated contacts. The electrodes 1801 and 1806 are externally insulated 1804 surrounded to be electrically isolated from it in block 130. Power cables could also be connected directly to the electrodes. The electrodes of FIG. 18 can approach and weld virtually any location of a layer of wire webs coated with a wire-guiding electrode 103. Also conceivable is a double Rollradelektrode as a secondary electrode consisting of two opposing each opposite polarity separate and insulated Rollradelektroden for resistance welding according to the principle of the electrodes of FIG. 19.

Fig. 20 shows a secondary electrode having a contact surface with a raster pattern. It is suitable for carrying out pointwise merging on wires that are still lying on one another with a cross section, thus reliably producing small areas that are fused together. The position with which the electrode 2001 touches should alternate for each successive layer, so that directly on areas of pointwise two fused wires of an overlying layer of the wire applied thereto is not fused at this point in this layer with the underlying layer and site, but only in the following layer above this point. Although this results in printed objects with less tensile strength against the layers and which are not airtight, but for the welds are easy to create and there is less Flitze and less oxidation of the material.

Explanations:

101 carrier plate, build platform 701 wire

102 object, object 702 electrode

103 wire-carrying electrode, 703 wire-carrying electrode,

wire-applying electrode, wire-applying electrode

primary electrode

104 wire 704 insulating layer

105 printhead 705 electrode, contact electrode

106 power cable, power cable 706 wire layer

107 power cable, power cable 801 wire-carrying electrode,

wire-applying electrode

109 Secondary electrode 802 wire

1 10 roll 803 structure

1 1 1 roll 901 wire

1 12 Motor axis, motor 902 Wire-carrying electrode

1 13 cooling fins 903 non-conductive material,

ceramic tip

1 14 grinding surface 904 metal part

1 15 Terminal 1001 stepper motor

1 16 bar 1002 cam Housing of the 3D printer 1003 camshaft

Knob 1004 locking ring

Display 1005 compression spring

Guide tube 1006 Torsion spring

Fan 1007 Contact surface, contact area Guide rail 1008 Radiator

Connection part 1009 fan

Rail 1010 connector

Belt 1 101 Secondary electrode

Timing belt pulley 1 102 Tip, electrode tip

Stepper motor 1201 Secondary electrode

Stepper motor 1301 electrode

Sheet metal 1302 Contact material, tip

Secondary Electrode Block 1401 Upper Part

Power cable 1402 Flat area

Secondary electrode 1403 Wire web, wire

Secondary Electrode 1404 Metal Part, Item Hole 1601 Structure

Electrode 1701 connection area

Lever 1702 structure

Spring 1801 electrode

Object, object 1802 Electrode

Construction platform 1803 Insulating layer

Power cable 1804 insulation

Motor, stepper motor 1805 electrode

Wire 1806 electrode

Channel 1901 electrode

Upper part 1902 shift

Funnel section, rounded 1903 electrode

Contact surface, area 2001 Electrode

Surface F force

Rounding d Diameter of the channel

Nut-shaped section R Center-line radius of wire Thread S Force

Wire-carrying electrode, primary q width of the wire

electrode

Mother-shaped portion D Inner diameter

Intermediate part b width

End area T height

Channel A height

Wire H Final height of the layer thickness Metal piece h Width of the wire

contact surface

rounding off

Claims

claims

1. A method of producing a metal article

a metal wire progressively in layers by means of a wire-carrying primary electrode in the resistance welding process stretched or spot welded,

wherein through the main body of the wire-guiding primary electrode, a channel passes through which the metal wire is guided in the solid state and led out into or directly below the mouth of this channel through which the metal wire from the wire-guiding primary electrode, laid out on an adjacent metal surface and stretched or is spot-welded, wherein the metal surface is a carrier plate, or a previously attached metal wire layer,

the method comprising the steps of:

(a) for stretch or spotwise resistance welding, passing an electric shock from the wire-guiding primary electrode through the metal wire to the adjacent metal surface,

(c) repeating steps (a) and (b) to form the article of metal layer by layer by subsequent spot welds and movements;

(D) passing a further electric current from a secondary electrode by means of steps (a) and (b) already stretched or point welded metal wire around this at least partially in addition, preferably on the entire in one or more of the steps (b) designed length to heat up and merge with the adjacent metal surface.

2. The method of claim 1, wherein during step (b) the metal wire is laterally bent at the mouth of the channel of the wire-guiding primary electrode.

3. The method of claim 2, wherein the bending of the metal wire by guiding and friction along the mouth of the wire-guiding primary electrode takes place, wherein the mouth preferably comprises a different material from the base material or from this consists, more preferably a ceramic material or a different metal.

4. The method of claim 2, wherein the bending of the metal wire is performed by heating the metal wire and moving the wire-guiding primary electrode.

5. The method according to any one of the preceding claims, wherein the channel of the wire-guiding primary electrode is open and corresponds to a laterally attached to the base notch through which the metal wire is guided and ends in an orifice to the lower surface of the wire-guiding primary electrode.

A method according to any one of the preceding claims, wherein the mouth of the channel of the primary wire-guiding electrode comprises an annular contact surface below which the metal wire can rotate around during application to be able to apply the metal wire in any direction of a plane and is designed to be at least transferring a portion of the current from the wire-carrying primary electrode to the metal wire.

A method as claimed in any one of the preceding claims, wherein the channel of the wire-guiding primary electrode above the mouth is wider than the remaining part of the channel to facilitate the bending of the metal wire.

8. The method according to any one of the preceding claims, wherein the wire-guiding primary electrode does not rest with the mouth on the metal wire during orders of the metal wire.

9. The method according to any one of the preceding claims, wherein the metal wire is preheated by means of a wire leading primary electrode upstream, second electrode by conducting a second current flow, wherein preferably the second electrode is disposed within the main body of the wire-guiding primary electrode.

10. The method according to any one of the preceding claims, wherein the leadership of

Metal wire through the channel by a motorized feed, preferably by adhesion via rollers, is supported.

1 1. A method according to any one of the preceding claims, wherein the cross section of the metal wire before its introduction into the wire-carrying primary electrode, preferably by rolling, is changed.

12. The method according to any one of the preceding claims, wherein in step (b) either the wire-carrying primary electrode, or the support plate, or both are moved.

13. The method of any one of the preceding claims, wherein step (d) further comprises applying a pressure to the heated metal wire.

14. The method according to any one of the preceding claims, wherein the electrical opposite pole of the secondary electrode, the support plate or another on the object of metal can be placed opposite polarity secondary electrode.

15. The method according to any one of the preceding claims, wherein the mouth of the wire-guiding primary electrode or the tip of the secondary electrode, if necessary, automated, preferably by means of an adjacently mounted grinding surface or a metal-removing tool, ground or reworked.

16. The method according to any one of the preceding claims, comprising a step of additional shaping of the article of metal during and / or after its completion by means of a movably arranged metal-removing tool, preferably a movably arranged grinding surface or a movably arranged cutter.

17. The method according to any one of the preceding claims, wherein the metal wire additionally comprises a sheath with fusible solder material, wherein the solder material has a melting temperature which is below that of the metal wire.

18. The method according to any one of the preceding claims, wherein the metal object after its completion is released from the carrier plate.

19. Apparatus for fabricating articles of metal by progressively layering and resistance welding a metal wire, comprising

a power supply designed to generate electrical surges for resistance welding,

a wire-guiding primary electrode for guiding and for spot or point-wise resistance welding of a metal wire, wherein the wire-carrying primary electrode is connected to the power supply,

a control unit for controlling the movement arrangement (s) and the power supply, wherein through the main body of the wire-guiding primary electrode, a channel extends through which the metal wire in the solid state can be passed through to a mouth of the channel and designed in or directly below this mouth on an adjacent metal surface and can be welded spotwise or pointwise,

wherein the metal surface is a carrier plate, or on a previously attached metal wire layer.

20. Apparatus according to claim 19, comprising means adapted to carry out the method according to one of claims 1 to 18.

21. Apparatus according to claim 19 or 20, wherein the mouth of the channel of the wire-guiding primary electrode comprises or consists of a different material from the base body, preferably a ceramic material or a different metal.

22. The apparatus of claim 19, wherein the mouth of the channel of the wire-guiding primary electrode comprises an annular contact surface and is configured to transmit at least a portion of the current from the wire-guiding primary electrode to the metal wire.

23. An apparatus according to any one of claims 19 to 22, wherein the channel above the mouth of the wire-guiding primary electrode is wider than the remaining part of the channel to facilitate the bending of the metal wire.

24. The apparatus of claim 19, further comprising a second electrode connected upstream of the wire-guiding primary electrode and configured to preheat the metal wire by conducting a second current flow, wherein preferably the second electrode is disposed within the main body of the wire-guiding primary electrode.

25. Device according to one of claims 19 to 24, further comprising a motorized feed is designed to guide the metal wire through the channel, preferably by adhesion via rollers to support.

The apparatus of any one of claims 19 to 25, further comprising rollers preceding the wire-guiding primary electrode and configured to change the cross-section of the metal wire prior to its insertion into the wire-carrying primary electrode.

27. An apparatus according to any one of claims 20 to 26, wherein the moving unit is configured to move either the wire-guiding primary electrode, or the carrier plate, or both.

28. An apparatus according to any one of claims 19 to 27, wherein the electrical opposite pole of the secondary electrode is the support plate or another on the object of metal attachable opposite pole secondary electrode.

29. An apparatus according to any one of claims 19 to 28, further comprising an adjacently mounted grinding surface or a metal-removing tool which / is suitable for post-grinding or reworking the mouth of the wire-guiding primary electrode or possibly the tip of the secondary electrode.

30. Device according to one of claims 19 to 29, further comprising a movably arranged metal-removing tool, preferably a movably arranged grinding surface or a movably arranged cutter, which is suitable for additional shaping of the article of metal during and / or after its completion.