DE102015008918A1 - Process for the additive production of three-dimensional components - Google Patents

Abstract

Method for the additive production of three-dimensional, metallic components (12), wherein the components (12) are built up in layers or sections by fusing a supplied metallic material to the component (12) under vacuum conditions. In order to achieve an improvement in the quality of the components produced, it is proposed that the fusion of the metallic material with the component (12) is carried out at a processing point by means of an arc (20), wherein the arc (20) by means of a laser (22) and / or electron beam is guided.

Description

The present invention relates to a method for the additive production of three-dimensional metallic components, wherein the components are built up in layers or sections by fusing a supplied metallic material to the component under vacuum conditions.

Such methods are for example from EP 1 296 788 B1 or DE 10 2013 108 111 A1 known. Usually, starting from a substrate which can also be used in the present invention, the material is applied in layers by applying a powder layer in individual steps, which is subsequently fused by means of the laser to the substrate at the points at which a material order is desired. This process is repeated until the desired component is produced, whereby complex three-dimensional structures are possible by the layered structure.

However, it has been shown that the required after each layer order another powder layer, which also also needs to be smoothed, on the one hand a fairly high amount of time required and on the other hand incurred relatively large amounts of powder that does not even with the Component be merged. It is understood that the residual powder in the known method is then obtained in particularly large quantities when the component to be produced has relatively many cavities and recesses with respect to the base surface.

When using laser beams to fuse the material, there is also a problem with additive production in that, owing to the relatively high heat input of a laser beam, which can have a light output of up to 4 kw, already produced material layers are remelted under the layer currently being processed can be what is undesirable in the sense of producing high quality components.

Also known is the application of material by means of an arc, the so-called build-up welding, but so far could not gain much importance in the context of additive manufacturing processes. In particular, when machining the workpieces to produce the component under vacuum, a major problem is that an arc in a vacuum often jumps uncontrollably, which in turn is detrimental to the quality of the component to be produced.

The object of the present invention is to improve a method of the type mentioned in that the quality of the components produced is improved.

According to the invention the object is achieved in that in a method of the type mentioned the fusion of the metallic material is carried out with the component at a processing point by means of an arc, wherein the arc is guided by means of a laser and / or electron beam.

It has been found that a particularly good combination of low heat input is achieved by the combination of an arc, which supplies the main melting performance for melting and fusing the supplied metallic material with the component, and a laser, possibly also an electron beam, which guides the arc in the previously generated layers of the component on the one hand and a fast material application with precise guidance of the processing point on the other hand is possible. It has been shown that under the guidance of a laser or electron beam, the arc no longer tends to uncontrolled blasting even under vacuum conditions, so that the position of a molten bath at the processing point can be performed on the one hand precisely, on the other hand, not deep into the already produced workpiece extends.

In a particularly preferred embodiment of the invention, the arc is focused by means of the laser beam and / or additionally ionized. By this measure, the quality of the material order can be further increased.

In principle, it is possible to supply the metallic material as a powder, wherein on the one hand it is possible, in a conventional manner, to apply the metallic material as a powder successively in layers to the already produced layers of the component and then with the aid of the laser and / or electron beam controlled Arc to melt where a material application is desired. To avoid unnecessary accumulation of metal powder, which is not necessary for producing a material application, it may be advantageous to fluidize the metallic powder in a gas stream and then to forward the gas stream to the processing site. It has been shown that significantly less excess powder is obtained by this measure, which is particularly advantageous in the course of the process in a vacuum chamber.

In a particularly preferred embodiment of the invention it is provided that the metallic material is supplied as a wire.

The wire can be supplied laterally or coaxially with respect to the laser and / or electron beam, wherein the wire can be supplied cold or possibly preheated to the range of the solidus temperature.

The wire can be supplied for example by a passage in the wall of a vacuum chamber via a pressure stage system but also via a wire supply within the vacuum.

Preferably, the wire is supplied as consumable electrons for forming the arc between the wire and the component.

This variant has the advantage that for carrying out the method within the vacuum chamber few parts are required, wherein the melting of the wire at the top takes place directly with the aid of the arc generated there. Preferably, the wire is movable in the feed direction and in the opposite direction, so that the arc can be controlled by a forward and backward movement. The back and forth can be used to refine the method also used to selectively dissolve drops on the tip of the wire and to minimize the heat input into the component.

Alternatively, a non-consumable electron may be used to form the arc, with the wire being fed to the processing site formed thereby. Of course, the position of the fixed electrode can of course be controlled variably to control the arc.

The arc can be generated with a direct current or with an alternating current. As a result, the magnetic fields produced by the welding current can be influenced and associated arc bubbles, spatter and the like can be positively influenced.

Preferably, the method is carried out in such a way that the processing point is formed stationary in a vacuum chamber, while the component is moved relative to the processing point during the application of material.

In the following, reference will be made in detail to two exemplary embodiments of the invention with reference to the attached drawings. Show it:

1 a longitudinal section of an apparatus for the additive production of a metallic component;

2 a longitudinal section of another embodiment of an apparatus for the additive production of three-dimensional metallic components.

In 1 is a device 10 shown with which a method for the additive production of a metallic component 12 , which is shown here as being under construction workpiece, in a vacuum chamber 14 is feasible. The component 12 or workpiece is mounted on a table, not shown in detail, which allows a method of the component in the X, Y and Z directions. The component 12 is produced in layers in the sense of additive production, ie in the

1 shown embodiment, a number of layers have already been applied, wherein the applied current material layer 16 is not shown to scale to scale for illustrative purposes. The first layer may be on a previously in the chamber 14 incorporated substrate can be constructed.

A vacuum pump 18 evacuates the inside of the vacuum chamber 14 to the usual in the field of thermal processing methods in vacuum pressures.

The fusing of supplied metallic material in the applied material layer 16 required energy input is through an arc 20 provided between a supplied as a metallic material wire 28 and the workpiece 12 is built. Since an arc under vacuum conditions tends to uncontrollably change position, it is a laser 21 arranged outside the chamber, which itself has only a relatively low light output, in the embodiment shown approximately 100 watts, which would not even be suitable to melt the material to the application layer 16 train.

A laser beam 22 the laser 20 is through an entrance window 24 in the wall of the vacuum chamber 14 to a processing point on the component 12 passed, at which by the mentioned arc 20 a molten bath 26 formed. A non-illustrated ventilation of the inside of the entrance window 24 Prevents metal vapor from condensing there. The laser beam 22 serves on the one hand the positioning of the arc 20 at the desired processing location and is also suitable to focus the arc and further ionize. In this way, it is possible with a comparatively small and low-power laser through the arc 20 to control generated melting energy and a high quality component 12 manufacture.

The wire 28 is by means of a very simplified illustrated wire feeder 30 the processing point on the molten bath 26 fed, passing through a vacuum feedthrough 32 in the wall of the vacuum chamber 14 supplied to the interior of the vacuum chamber and delivered, for example, by driven friction rollers. For the formation of the arc is arranged outside the vacuum chamber DC power source 34 arranged, their negative polarity with the wire 28 and their positive polarity with the workpiece 12 connected is. Voltage and efficiency of the power source 34 are designed such that the arc 20 between a wire end 36 and the workpiece 12 in the place of the molten bath 26 can train. The wire feeder 30 is suitable for moving the wire in both directions, ie to the molten bath 26 away, but also away from the molten bath, on the one hand the arc 20 On the other hand, for a targeted replacement of molten metal at the wire end 36 to provide and overall the energy input into the workpiece 12 minimize as much as possible to melt under the current material layer 16 To avoid already generated material layers. It is also readily possible, instead of a DC source 34 to use an AC power source to generate the arc, which may possibly be positively influenced by the welding current resulting magnetic fields and the associated so-called Arch-Blows and metal splashes.

The current flow in the wire 28 between a connection point 38 the power source and the arc 20 also has the consequence that the wire heats up, which is generally positive in terms of a reduced heat input into the workpiece 12 affects because the arc performance for melting and application of the metallic material can be set smaller.

In 2 is another device 10 shown in many structural details of the previously presented device 10 according to 1 corresponds and has therefore been provided in the same matching components with the same reference numerals. Deviating executed in this embodiment that the wire 28 itself is not designed to form the arc as a consumable electrode, but a non-consumable, fixed electrode 128 is provided between the electrode tip 136 and the molten bath 26 the arc 20 is trained. The wire 28 is otherwise in the manner described above using a wire feed 30 delivered, in turn, a delivery, but also a retraction of the wire 28 from the molten bath. The wire is through a vacuum feedthrough 32 led into the interior of the vacuum chamber. The arc 20 is again by means of a DC power source 134 applied, its negative polarity with the welding electrode 128 and their positive polarity with the workpiece 12 connected is. The power source 134 again lies outside the vacuum chamber, with leads 135 are guided by appropriate vacuum-tight passages in the chamber interior.

To the wire 28 to preheat in this embodiment is an inductor 150 provided, its power supply outside the vacuum chamber 14 is arranged, with a coil 152 for generating eddy currents in the wire 28 wraps it helically. The eddy currents ensure a heating of the wire, so that in turn by the arc 20 applied heat input can be kept low to the lowest possible melting below the applied material layer 16 to minimize previously applied material layers.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1296788 B1 [0002]
• DE 102013108111 A1 [0002]

Claims (12)

Method for the additive production of three-dimensional, metallic components ( 12 ), the components ( 12 ) layer or section by fusion of a supplied metallic material with the component ( 12 ) are constructed under vacuum conditions, characterized in that the fusion of the metallic material with the component ( 12 ) at a processing station by means of an arc ( 20 ), the arc ( 20 ) by means of a laser ( 22 ) and / or electron beam is guided. Method according to claim 1, characterized in that the arc ( 20 ) using the laser ( 22 ) and / or electron beam focused and / or additionally ionized. A method according to claim 1 or 2, characterized in that the metallic material is supplied as a powder. A method according to claim 3, characterized in that the metallic powder is applied in layers on a previously applied layer of the component and then the desired portions are fused. A method according to claim 3, characterized in that the metallic powder is fluidized in a gas stream and the gas stream is supplied to the processing site. Method according to claim 1 or 2, characterized in that the metallic material is used as wire ( 28 ) is supplied. Method according to claim 6, characterized in that the wire ( 28 ) as a melting electrode for the formation of the arc ( 20 ) between the wire ( 28 ) and the component ( 12 ) is supplied. Method according to claim 7, characterized in that the wire ( 28 ) is moved in the feed direction and in the opposite direction to the arc ( 20 ) to control. Method according to claim 8, characterized in that by moving the wire back and forth ( 28 ) from a wire end ( 36 ) Drops of molten metal are removed and the heat input is minimized in the already generated layers. Method according to claim 6, characterized in that the arc ( 20 ) between a non-consumable electrode ( 128 ) and the component ( 12 ) and the wire ( 28 ) is supplied to the processing station formed thereby. Method according to one of the preceding claims, characterized in that the arc ( 20 ) is generated with a direct current or an alternating current. Method according to one of the preceding claims, characterized in that the processing point in a vacuum chamber ( 14 ) is formed stationary while the component ( 12 ) is moved relative to the processing point during the material application.

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