DE112005003693T5 - Pressure cell and printhead for printing molten metals - Google Patents

Abstract

printhead for discharging an electrically conductive liquid, with at least one helical ring with a ring axis, at least a substantially parallel to the ring axis arranged feed channel and at least one ejection channel that is substantially orthogonal is arranged to the ring axis, wherein the at least one ejection channel is connected to a first and a second electrode, the are aligned with each other and substantially orthogonal to Ring axis and the discharge channel are arranged.

Description

FIELD OF THE INVENTION

The This invention relates generally to a system and method for manufacturing three-dimensional metal objects, as for example used in the manufacture of massive freeform molds. More accurate said, the invention relates to a printhead for printing liquefied Metals, such as aluminum, magnesium, bronze, titanium or steel, in the form from droplets or as a continuous stream to one Carrier to use the printed materials 2D or 3D objects manufacture. By controlling the movement of the printhead and the Carrier relative to each other can be a part layer for Layer to be built. This is especially in the fast production and the production of massive freeform forms of utility.

BACKGROUND OF THE INVENTION

On the field of inkjet printers and metal sprayers are ejection techniques for liquid droplets well known. Inkjet printers typically produce a printed image by ejecting water-based inks or hot melt waxes through an opening on the ambient or a relative low temperature. For making the ejection mechanisms for this printer is due to the low temperature of the printing process a wide variety of materials used. For example Piezoelectric crystals are used to produce an electrical Signal to convert an acoustic signal to an ink droplet low temperature. In another example a bunch of fine wires is used to to transmit an ultrasonic pulse to an ink meniscus, to eject an ink droplet at low temperature. At temperatures above 600 ° C, piezoelectric decomposes Materia lien and bundles of fine wires, or they provide their function and are therefore unsuitable.

The document GB 1472939 was founded in 1977 by Osprey Metals Ltd. filed, and it is directed to a metal spray device. The device described emits droplets that follow unpredictable paths and can not be used to build accurate structures.

The document US 5257657 was filed in 1993 by Incre Inc. (USA) and describes the preparation of a three-dimensional free-form solid-phase objet from droplets of liquid phase material having substantial surface tension and well-defined solidification properties. The liquid phase material is ejected in discrete droplets from an ejection head onto a support. The temperature, frequency, size and trajectory of the droplets as well as the relative speed of movement between the carrier and the ejection head are adjusted to compensate for the physical properties of the liquid phase material and the heat dissipating properties of the growing object to form a desired object.

The document US 5171360 was submitted in 1992 by the University of Southern California, and describes a method of making a product by directing a flow of liquid from a nozzle to a collector in the form of the desired product. By applying a disturbance to the liquid flow, a stream of droplets is generated. The described device for producing a reticulated product has an under. A pressurized source of molten material, a holder for positioning a product collector in a chamber, wherein the collector determines a desired product, and a droplet flow generator positioned in the chamber. The apparatus further includes a conduit for conducting molten material from the material source to the generator nozzle, a mechanism, typically a modulator, for perturbing the droplet stream, and a drive mechanism for relative movement of the nozzle and the holder.

The document submitted in 1997 by Davon Gore US 5598200 is directed to a relatively complicated apparatus for on-demand ejection of a discrete liquid droplet at a high temperature along a predetermined path by transferring a physical impulse from a low temperature environment to a high temperature environment. The ejector has a receptacle with an interior containing a high temperature liquid such as liquid metal (aluminum (Al), tin (Sn), zinc (Zn)). The interior has an inlet end with a heat-insulating pulse transmitting device, a feed for the droplet material, and a discharge area with a mouth through which the discrete droplets are ejected. An inert gas is fed into the container through the inlet end to create an overpressure over the liquid. Increasing the overpressure increases the droplet size. A heater heats the material absorbed inside. A pulse generator is connected which imparts a physical pulse to the impulse transmission device to produce an ejection pressure at the orifice to expel a discrete droplet of the high temperature liquid.

The document US 6149072 was submitted in 2000 by the University of Arizona, and it is directed to a droplet of voting system and a method for freeforming three-dimensional objects. Molten metal is ejected as a continuous stream under the influence of gravitational forces. The current is broken up into droplets by a disturbing vibration, which is induced mechanically or acoustically in the molten bath. In order to build mechanical parts, the continuous stream of droplets must be switched on and off - or alternatively, 'unwanted' droplets must be deflected by electrostatic forces to a collector that prevents desired droplets from reaching the target. Many droplets can be created side by side to form a line. Also shown in the drawings is a matrix printhead with individually activated nozzles.

The document US 5960853 was filed in 1999 by Aeroquip Corp. (USA) and describes an apparatus for producing a three-dimensional freeform article using a layered deposition of a molten metal. Essentially, the same method is used to generate droplets as described in U.S. Pat US 6149072 is described. The production of a three-dimensional part is described in detail.

The document US 6202734 was acquired by Sandia Corp. in 2001. (USA), and it describes a relatively bulky and complicated apparatus for supplying droplets of molten metal for producing parts of metal. The apparatus has means for supplying molten metal, means for heating molten metal to remain liquid while inside the apparatus, means for applying a magnetic field in a direction orthogonal to the means for feeding molten metal molten metal, means for transmitting an electric current directly to the molten metal to apply a force in a first direction thereto. The magnetic field is generated by a permanent magnet, which limits the application to temperatures below 500 ° C. The patent shows the design of a single cell using a layer strategy.

PROBLEM TO BE SOLVED

It An object of the invention is to provide a printhead which suitable for ejecting liquid metal, where he has a simple and robust design. Furthermore, it is an object to control the ejection process, like the ejection time, the amount of ejected Material, the ejection speed and other relevant Control process parameters. It's another job, one Printhead to create molten metals, such as liquid Steel or aluminum and other metals, at very high temperatures can emit. It is another object of the invention a printhead with a modular design, with several pressure cells, which can be activated and controlled individually, to accomplish. It is still another object to have a printhead with a Construction to create, which is suitable for miniaturization, so emitted very small amounts of liquefied material can be.

SUMMARY OF THE INVENTION

The Invention is directed to a pressure cell and a print head, which consists of several individual pressure cells, each of which is so is constructed that a demand-oriented ejection of a specified amount of liquid material possible is when a command is received from the outside.

The Operating principle of a preferred embodiment of a Pressure cell based on magnetohydrodynamic pumping (from now as MHD pumps called). The MHP pumps have a Lorentz force on a moving charge that is in the working range of a magnetic field lies. By two electrodes connected to an electrically conductive Liquid in a channel in contact, becomes a voltage placed on this electrically conductive liquid in the channel, so that a current flows between the two electrodes, so that there are moving charges. Because of a magnetic field essentially orthogonal to the general direction of the flow and to Flow channel is created, such a force is on the liquid in the channel is exerted by it this is pumped.

A printhead generally has a helical ring for generating a magnetic field and at least one feed channel disposed substantially parallel to the ring axis. Discharge channels are connected to at least one feed channel and are arranged substantially orthogonal to the ring axis and to the feed channel. Each ejection channel has two aligned electrodes which are in contact with the liquefied material ready to be expelled in the ejection channel. The electrodes are arranged substantially orthogonal to the ring axis and to the ejection channel. To eject a specified amount of liquefied material through the ejection channel, a magnetic field is generated by the ring by applying a first voltage thereto. By applying a second voltage to the electrodes, there exists a current and thus moved charges in the liquefied material between the electrodes. As a result, a Lorentz force is generated parallel to the discharge channel, which acts on the liquefied material, so that this out in a defined manner from the discharge channel will come across. Depending on the size of the ejection channel and the ejection head, it is possible to eject droplets having a diameter of, for example, 100 μm, or eject material as a continuous stream of material.

If it is expedient, is the discharge channel with a discharge nozzle for accurately shaping the ejected from the discharge channel Beam provided in the required manner. Dependent From the application area, the ejection nozzle has over a convergent or a divergent fluid channel, or a combination of the two (convergent-divergent), wherein the convergent channel in the flow direction of a wide Diameter is narrowed to a smaller diameter and the divergent Channel from a smaller diameter to a larger one is widened. The side walls of the nozzle can be straight, concave or convex. For example, by a Convergent nozzle accomplished with convex sidewalls, that at the outlet of the nozzle results in a fast liquid jet. Depending on the material to be ejected, it is of Advantage if the opening at the nozzle outlet sharp Has edges or a bevel so that an exact tear-off edge is set. The ejection nozzle preferably consists of a heat-insulating material, so that the material to be ejected is not superfluous Heat energy is subtracted. If it is expedient can the ejection nozzle on the outer contour of the printhead survive the distance between this and the wearer.

If it is expedient to have one or more ejection channels with the outside environment or through a relaxation channel be connected to a gas supply. Through the relaxation channel may be a gas or other suitable fluid in the discharge channel delivered / sucked when the print material is accelerated. Thus, in the area where the expansion channel on the discharge channel meets, a separation of the liquid between the electrodes and a liquid supply be accomplished, so that only a small mass of the liquid to be ejected has to be accelerated. After ejecting a quantity of liquid replaces the supplied liquid again sucked Gas, and the discharge channel is completely with filled with the working material.

Around a freezing of the in the feed and in the discharge channel To avoid existing material, it must be heated. This can be realized by constructing the ring so that it provides sufficient residual heat, and / or by that an additional heater inside and / or is placed outside the ring. By modifying the amplitude and sign of the first and second voltages Is it possible to apply the material to be ejected acting force and thus the behavior of the ejection process to set exact.

Due to the fact that a pressure cell can print metals such as aluminum, steel, bronze, titanium and other metal materials in their liquid form, the materials used for the pressure cells and the print head must be thermally stable at the melting point of the materials to be ejected and in a certain range thereof be. Suitable electrically conductive materials useful for the electrically conductive portion of the device include, for example, tungsten having a melting point of 3422 ° C or tantalum having a melting point of 3017 ° C. It should be noted that depending on the field of application, other materials may be suitable. Suitable electrically insulating materials are those from the group of ceramics such as aluminum oxide (Al ₂ O ₃ ), which is also referred to as alumina. Alternatively, other materials with high temperature stability may be suitable. All materials in contact with the liquid metal to be ejected should be thermally stable at high temperatures and not be dissolvable by the liquid metal.

A preferred embodiment of a pressure cell according to the Invention preferably has a structure from layers of electrically conductive and non-conductive materials, which are combined in a single layer. The individual layers of the Materials can, for example, by punching various Forms of thin material layers are produced. Then The single layers are assembled so that at least one Part of the electrically conductive material by an electrically not surrounded by conductive material. To assemble the device the individual layers of the material are given to each other, that between them in a special area an electrical shear Contact sets. The individual layers can interact be connected, for example, by sintering or another suitable process. Alternatively, or in addition offers the layer structure the possibility of the single layers clamp, what a simple assembly and disassembly allows the device.

By the layer structure, it is possible to use a printhead with a three-dimensional spiral ring and several pressure cells for ejection of liquefied material. It will the ring axis of the three-dimensional ring normally parallel to at least one feed channel for liquefied Material and parallel to a connected with this discharge channel arranged.

• a) Eine erste Schicht verfügt über eine Schicht aus einem isolierenden Material um ein Verbindungsgebiet aus einem elektrisch leitenden Material herum, das dazu geeignet ist, zwischen zwei benachbarten Schichten einen elektrischen Strom zu leiten. Die Schicht verfügt ferner über eine Durchgangsöffnung, die im Isoliermaterial ausgebildet ist und Teil eines Zuführkanals ist, der auszustoßendes Material von einem Materialvorrat an einen in einer benachbarten Schicht angeordneten Ausstoßkanal liefern kann.
• b) Eine zweite Schicht mit ebenfalls einer Durchgangsöffnung für verflüssigtes Material, die Teil des Zuführkanals ist. Die Durchgangsöffnung ist normalerweise im Isoliermaterial angeordnet, und sie ist zur Durchgangsöffnung der ersten Schicht ausgerichtet. In der zweiten Schicht ist die Durchgangsöffnung mit einem Ausstoßkanal im Isoliermaterial verbunden, das mit einer ersten und einer zweiten Querelektrode verbunden ist, die zueinander ausgerichtet sind und im Wesentlichen orthogonal zum Aus stoßkanal angeordnet sind. Die zweite Schicht verfügt ferner über ein Verbindungsgebiet aus einem elektrisch leitenden Material, das das Verbindungsgebiet der ersten Schicht mit einem weiteren Verbindungsgebiet einer dritten Schicht elektrisch verbindet. Das Verbindungsgebiet ist zumindest teilweise durch Isoliermaterial umgeben.
• c) Eine dritte Schicht entspricht im Wesentlichen dahingehend der ersten Schicht, dass sie ebenfalls über eine im Isoliermaterial angeordnete Durchgangsöffnung für verflüssigtes Material verfügt. Eine Verbindung aus elektrischem Material ist so angeordnet, dass sie an einer Zusammenbauposition der Vorrichtung elektrisch mit dem Verbindungsgebiet der zweiten Schicht und einem Ringgebiet der vierten Schicht verbunden ist.
• d) Eine vierte Schicht verfügt über ein Gebiet aus Isoliermaterial mit einer Durchgangsöffnung, die mit denen der anderen Schichten ausgerichtet ist. Die vierte Schicht verfügt ferner über ein Ringgebiet aus einem elektrisch leitenden Material in gebogener, falls geeignet, rechteckiger Form. In der zusammengebauten Vorrichtung ist das Ringgebiet elektrisch mit den Verbindungsgebieten benachbarter Schichten verbunden.

An embodiment of a pressure cell according to the invention has the following four layered construction:

• a) A first layer has a layer of an insulating material around a connection region of an electrically conductive material, which is adapted to conduct an electric current between two adjacent layers. The layer also has a through hole formed in the insulating material and forming part of a feed channel capable of delivering material to be ejected from a supply of material to an ejection channel located in an adjacent layer.
• b) A second layer also having a through hole for liquefied material which is part of the feed channel. The through hole is normally disposed in the insulating material and is aligned with the through hole of the first layer. In the second layer, the through-hole is connected to an ejection channel in the insulating material, which is connected to a first and a second transverse electrode, which are aligned with each other and arranged substantially orthogonal to the push channel. The second layer further includes a connection region of an electrically conductive material that electrically connects the connection region of the first layer to another connection region of a third layer. The connection area is at least partially surrounded by insulating material.
• c) A third layer substantially corresponds to the first layer in that it also has a through hole for liquefied material arranged in the insulating material. A compound of electrical material is arranged so as to be electrically connected to the connection region of the second layer and a ring region of the fourth layer at an assembling position of the device.
• d) A fourth layer has an area of insulating material with a through hole aligned with that of the other layers. The fourth layer also has a ring region of an electrically conductive material in a bent, if appropriate, rectangular shape. In the assembled device, the ring region is electrically connected to the connection regions of adjacent layers.

In a preferred embodiment, the layers of a pressure cell have a typical thickness in the range of 0.1 mm to 1 mm. In a preferred embodiment, the helical ring has a typical cross section in the range of 0.5 to 5 mm ² . However, other dimensions may be appropriate depending on the field of application.

at a preferred embodiment of an assembled Printhead form when the multiple pressure cells stacked are, the ring area of the last (fourth) layer and the connection areas the other layer is an electrical ring with a substantially helical curved shape, where at the axis of the ring substantially orthogonal to the electrodes and the ejection channel is located and through the center of the area between the electrodes runs. When the electric ring with a current sufficient Strength is essentially building a magnetic field orthogonal to the ejection channels and the electrodes the pressure cells. By waste heat of the electric ring and / or An additional heating element is in the feed channel and in the discharge channel existing metal in liquid Condition held so that it passes through the at least one discharge channel can be ejected. The individual layers of a pressure cell can have the same or different thicknesses feature. If appropriate, more can Layers may be provided to add additional features.

A preferred pressure cell according to the invention has at least one feed channel having at least one Output channel is connected, which is substantially orthogonal is arranged to the passageway. The at least one ejection channel is connected to a first and a second electrode. The passageway can be inside an electric helical ring, or outside the same, which is capable of a magnetic field substantially orthogonal to the discharge channel and the electrodes. If appropriate, the feed channel is pressurized, for example, by gas pressure to move the material in the direction of Push away ejection channel. In certain embodiments the discharge channel has a valve, for example in the form of a cross slide, around the mold and the opening of the ejection channel or to completely control it close.

Around to be able to create a pressure cell with small dimensions a simple design is used. All features are designed in such a way that they are made using a layer manufacturing process can be produced. That way, a single one Pressure cell can be built from four different layers, such as described above. An ejection layer has the ejection channel and the two electrodes. Two spacers (See the above points a) and c)) form insulating walls the channels for liquid metal. The Magnetic field is generated by a built-in layers in the ring. All layers have a through channel in common with one Stock is connected to liquid material. When the layers 1 to 4 are stacked together, they form a pressure cell.

It Any number of pressure cells can be stacked, to build a printhead. In a printhead, every cell can individually activated by a current through the electrodes is sent. The rings of the individual pressure cells are interconnected connected to form a single winding with multiple windings.

One Printhead can have more than one ring, to achieve special magnetic fields or special effects to eject several materials at the same time. The Rings are usually parallel to each other or adjacent to each other arranged. As stated above, the printhead can over have one or more ejection channels that essentially parallel to one another and to the ring axis of the one or the plurality of rings are arranged. The ejection channels can be arranged in the same or in different rings be that for each feed channel and the so connected discharge channel create an individual field. Each feed channel is connected to a series of ejection channels, which are arranged adjacent to each other or in an array. One Printhead with more than one feed channel provides the opportunity simultaneously eject different materials from a printhead.

Of the Printhead can be used to make a liquid metal to eject (print) onto a powder bed. The area the powder bed surface experiences when liquid Metal is printed on it, connecting through this liquid Metal, creating a completely dense, solid metal layer is formed. After a new layer of powder sprayed on the previous one printing, the next layer may begin printing. By this method, a solid freeform metal part can be produced become. Loose powder remains as a support structure in place and will be removed after the part is set up.

A preferred embodiment of a control unit for Controlling the ejection of material by a printhead According to the invention is constructed so that the Current and the voltage, as the electrodes and / or the ring be fed, synchronously controllable, so that the Ejecting the material droplets accurately adjusted can be.

BRIEF DESCRIPTION OF THE DRAWINGS

The The invention described herein will become more detailed from the following Description and the attached drawings that are not are to be construed as indicated in the appended claims limited invention, more complete be understood.

1 shows the construction of a first pressure cell and a first printhead;

2 shows the interior of a printhead according to the 1 without insulating material;

3 shows a second embodiment of a printhead as a perspective view;

4 shows the printhead the 3 without outer housing.

DETAILED DESCRIPTION PREFERRED EMBODIMENTS

One a better understanding of the invention is achieved by the present invention get detailed description that when related with the accompanying drawings is preferred Embodiments of the invention described herein sets forth. It should be noted that corresponding elements in different Figures generally marked with corresponding reference numerals are.

The 1 shows a first embodiment of a printhead 1 , a pressure cell 2 and several layers of a pressure cell 2 in perspective view. The printhead 1 consists of several pressure cells 2 which are aligned in the transverse direction and are operatively connected to each other. A pressure cell 2 according to the described embodiment has substantially four layers 3 . 4 . 5 . 6 with acting as a housing areas 7 made of insulating material and areas 8th . 14 . 15 . 16 made of conductive material.

A first shift 3 has an area of insulating material 7 around a connection area 8th of electrically conductive material suitable for between two adjacent layers 4 . 6 to conduct an electric current. The first layer also has a passage opening 9 , which is arranged in the insulating material and part of a feed channel 10 is (essentially the x-direction) suitable for ejecting material from a supply of material (see US Pat 2 ) to one in a neighboring layer 4 arranged discharge channel 11 to deliver.

A second layer 4 also has a passage opening 9 for liquefied material, which is part of the feed channel 10 is. The passage opening 9 is usually in an area of insulating material 7 arranged, and it is to the passage opening 9 the first layer 3 aligned. In the second layer 4 is the passage opening 9 with a discharge channel 11 in the insulating material 7 connected to a first and a second transverse electrode 12 . 13 is connected, which are arranged in the y-direction and aligned with each other. As it recognizes bar, are the electrodes 12 . 13 essentially orthogonal to the discharge channel 11 arranged, which runs substantially in the z-direction. The second layer 4 also has a connection area 14 made of a conductive material, which is the connection area 8th the first layer with another connection area 15 the third layer 5 connects electrically. As can be seen, the second layer features 4 in the illustrated embodiment via a valve in the form of a cross slide 27 , The slider 27 allows modification of the cross-section or complete closure of the ejection channel as it is moved into or out of it. The second layer 4 here also has a relaxation channel 26 that the discharge channel 11 connects with the outside. Through the relaxation channel 26 can gas in the exhaust duct 11 be sucked when the liquefied material is accelerated. Thus, a separation of the liquid between the electrodes and the supplied liquid can be accomplished, which means that only a small mass of the liquid to be accelerated must be accelerated. After discharging a liquid amount, the supplied liquid replaces the sucked gas again, and the discharge channel is completely filled with the working material. The expansion channel in the embodiment shown here is at an angle with respect to the discharge channel 11 arranged so that a good separation of the material is achieved. It can be seen that, depending on the field of application, the cross slide 27 and the relaxation channel 26 need not be present in a pressure cell.

A third layer 5 essentially corresponds to the first layer 3 in that they also have a passage opening 9 For liquefied material features by insulating material 7 is surrounded. The connection area 15 of electrically conductive material is arranged to be electrically connected to the connection region in the assembled position of the device 14 the second layer and a ring area 16 the fourth layer 6 connected is.

The fourth shift 6 has an area of insulating material 7 around a passage opening 9 aligned with those of the other layers (the alignment is shown by dashed lines). The fourth layer also has a ring area 16 made of electrically conductive material. The ring area 16 has in the layer plane over substantially arched shape, which the passage opening 9 surrounds with a certain distance.

The 2 shows an assembled printhead 1 , wherein the insulating material acting as a housing 7 (see the 1 ) Areas 8th . 14 . 15 . 16 made of conductive material, it being the feed channel 10 forms. This makes it possible to use the three-dimensional spiral ring 17 to be recognized by the electrical interaction of the connection areas 8th . 14 . 15 and the substantially circular ring areas 16 is formed. Inside the ring 17 is liquefied material 18 schematically as recognizable as it is in the feed 10 and in the discharge channel 11 (see the 1 ) is housed. Ejecting the material 18 is through the across to each discharge channel 11 arranged electrodes 12 . 13 controlled. The feed channel 10 is with a material feed stock 19 connected by the printhead 1 material to be ejected is present. During operation, the material to be ejected becomes 18 - By heating at least in the feed 10 - held at a temperature above the melting point.

During operation, a voltage from a first power supply 20 to the ring 17 supplied so that flows through this a current. As a result, a magnetic field is generated, which is schematically represented by an arrow B (x-direction). The ring 17 and the power supply 20 can be designed so that the ring 17 generates enough waste heat to the ejected material 18 in the feed channel 10 and in the ejection channels 11 to keep in liquefied state. Ejecting the material 18 through the ejection channels 11 is through the electrodes 12 . 13 controlled by a voltage of a second power supply 21 to each of them by a switch 22 (only the connection with the first two electrodes is shown here - all other electrodes are activated in a similar way). By closing the switch 22 electric charges flow through the electrodes 12 . 13 and the liquefied material present therebetween, as schematically represented by an arrow Q (y-direction). As a result, a force F acts on the area of action of the electrodes 12 . 13 existing material, resulting in a discharge of a precise amount of material from the discharge channel 11 leads. The ejection of material droplets 23 is demonstrated in a simplified way. The amount and speed of the ejected material depend mainly on the voltages of the first and second power supplies 20 . 21 , the length of the supplied pulse and the amount of the moved charges between the first and second electrodes 12 . 13 be replaced. Other parameters are due to the shape of the electrodes 12 . 13 supplied pulse. Alternatively or additionally, the ejection of the material 18 by the shape of the voltage of the first power supply 20 to be controlled.

The 3 and 4 show a further embodiment of a printhead 1 on together built way. The 3 shows the printhead 1 as a perspective view from below with a housing, and the 4 shows the same printhead 1 as a second perspective view from below without housing (without the layers of insulating material 7 ).

The illustrated embodiment also has an ejection nozzle 25 at the end of each ejection channel 11 is arranged and serves to form droplets of accurate shape. The ejection nozzles 25 consist of a material that is thermally stable even at temperatures above the melting temperature of the materials to be ejected. In contrast to the embodiment of 1 and 2 are the ring areas 16 in this embodiment is substantially rectangular, resulting in a "longer" magnetic effect in the area in which the electrodes are arranged.

Summary:

The Invention is electrical to a printhead for ejecting conductive liquids at high temperatures, in particular molten metals, addressed. The operating principle is based on magnetohydrodynamic Pumping, applying a magnetic field and an electric field become. The printhead has a spiral ring for generating a magnetic field and at least one parallel to the Ring axis arranged feed channel. discharging passages are connected to at least one feed channel, and they are arranged orthogonal to this and to the ring axis. Each discharge channel has two aligned electrodes orthogonal to the ring axis and to it. To a specified amount of liquefied material through the discharge channel eject a first voltage is applied to the ring to generate a magnetic field, and a second voltage is applied put the electrodes. In a preferred embodiment the print head has a layer structure.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• GB 1472939 [0003]
• US 5257657 [0004]
• US 5171360 [0005]
• US 5598200 [0006]
• - US 6149072 [0007, 0008]
• US 5960853 [0008]
• US 6202734 [0009]

Claims (28)

Printhead for ejecting an electric conductive liquid, with at least one spiral ring with a ring axis, at least one substantially parallel to Ring axis arranged feed channel and at least one Ejection channel, which is substantially orthogonal to the ring axis is arranged, wherein the at least one ejection channel with a first and a second electrode is connected to each other are aligned and substantially orthogonal to the ring axis and are arranged to the discharge channel. Printhead according to claim 1, which has a Heating device has to put it at a certain temperature the melting temperature of a material to be ejected hold. A printhead according to claim 2, wherein the heating means consists of at least one spiral ring. Printhead according to one of the preceding claims, which has at least two spiral rings. Printhead according to claim 4, wherein the at least two spiral rings are arranged parallel to each other. Printhead according to claim 4, wherein the at least two spiral rings are arranged concentrically to each other. Printhead according to one of the preceding claims, the at least two feed channels each of which has at least one discharge channel connected is. Printhead according to claim 7, wherein at least two Feed channels within the same spiral ring or different spiral rings are arranged. Printhead according to claim 7, wherein at least one Feed channel outside at least one helical ring is arranged. Printhead according to one of the preceding claims, in the at least one ejection channel an ejection nozzle having. A printhead according to claim 10, wherein the ejection nozzle has a convergent and / or a divergent shape. Printhead according to one of the preceding claims, wherein the ejection channel is an ejection port having a round or rectangular cross-section. Printhead according to one of the preceding claims, in which the ejection channel is connected to a relaxation channel is so that the material to be ejected during the ejection process is disconnected. A printhead according to claim 13, wherein the material is separated by gas flowing through the expansion channel. A printhead according to claim 13 or 14, wherein the Expansion channel the discharge channel with the outside combines. Printhead according to one of the preceding claims, in which the supply channel is under pressure. Printhead according to one of the preceding claims, in which a voltage applied to the ring and / or the electrodes leads to a force on the ejected Liquid in the direction either to the ejection opening or away from it. Printhead according to one of the preceding claims, wherein the ejection channel is a valve for modifying its Has cross section. The printhead of claim 18, wherein the valve is out of a cross slide exists. Printhead according to one of the preceding claims, the interconnected, adjacent to each other Pressure cells, each of which forms part of the feed channel, having a part of the helical ring and an ejection channel. A printhead according to claim 20, wherein the pressure cells a layer structure of insulating material and electrically conductive Have material. The printhead of claim 21, wherein the pressure cell comprises: a) a first layer having an area of insulating material having a through opening and a first connection area of an electrically conductive area; b) a second layer having an area of insulating material with a through hole aligned with that of the first layer, an ejection channel and a second connection area of electrically conductive material for connecting the first connection area of the first layer to a third connection area of a third layer; c) a third layer having an area of insulating material, a through-hole aligned with that of the second layer, and a third a connection region of electrically conductive material for connecting the second connection region of the second layer to a ring region of a fourth layer; d) a fourth layer having an area of insulating material with a through hole aligned with that of the third layer and a ring area of electrically conductive material for connecting the third connection area of the third layer to a connection area of a next layer. A printhead according to any one of claims 21 or 22, in which the layers are interconnected by sintering. A printhead according to any one of claims 21 or 22, in which the insulating material consists of the group of ceramics and the electrically conductive material from the group of tungsten and tantalum exists. A printhead according to claim 22, wherein the annulus area is arcuate. A printhead according to claim 22, wherein the annulus area is rectangular. Printhead according to one of claims 23 to 26, in which each ejection channel is an ejection nozzle for Ejecting material has. A printhead according to claim 27, wherein the material the nozzle is made of sapphire.