Process for smoothing a surface of an additively manufactured, electrically conductive component

Abstract

Method for smoothing a surface of an additively manufactured, electrically conductive component (10), having the following features: a) the method uses a supply conductor (14) which is connected at one end to a high-frequency power source (30) and which has at another end a supply conductor connection (12) for the component (10), b) the method further uses a return conductor (13) which is connected at one end to the high-frequency power source (30) and which has at another end a return conductor connection (11) for the component (10), c) the high-frequency current source (30) to be used is designed such that a high-frequency current pulse can be emitted which is adjustable with regard to a frequency, a pulse duration and a voltage level, such that the steps of the method are: d) connecting the supply conductor connection (12) and the return conductor connection (11) to the component (10) such that the supply conductor connection (12) and the return conductor connection (11) are spaced apart from each other, e) applying a high-frequency current pulse to the component (10) such that • that the frequency of the high-frequency current pulse is selected so that a skin effect occurs and • that the pulse duration and the voltage level of the high-frequency current pulse are set so that the surface of the component (10) melts at least partially while smoothing the surface.

Description

The invention relates to a method for smoothing a surface of an additively manufactured, electrically conductive component.WO 2018 / 194481 discloses an additive manufacturing method. A workpiece is positioned on a construction platform of a parts construction module of an additive manufacturing apparatus. Electrical contacts are attached to the workpiece. The electrical contacts are connected to a power source. A layer of powdered metal material is deposited on the build platform and a surface of the workpiece is positioned on the build platform. In this way, the workpiece is embedded in a bed of the powdered metal material. A direct resistance heating of the workpiece is then carried out by supplying the workpiece with the electric current from the power source via the electrical contacts attached to the workpiece. Finally, one or more portions of a surface of the layer of powdered metal material are selectively scanned by an energy beam arrangement, thereby melting or sintering the selectively scanned portions on the underlying workpiece.US 3708645 A1 discloses a method for heating a workpiece. A workpiece formed from compacted, electrically conductive particles is heated by first passing a high-frequency current through the workpiece and then inductively heating the workpiece.Electrically conductive components manufactured as additives generally have a rough surface by the production method. The roughness of the surface represents a disadvantage of additively manufactured metallic components. The rough surface reduces the fatigue strength since unevennesses can serve as crack initiators. Also, the rough surface presents a problem in other applications. Thus, the rough surface may deteriorate the current conduction properties at high frequency alternating currents. This has a negative effect on their properties, in particular in the case of additively manufactured high-frequency conductors and antennas.For machining the surface of additively manufactured metallic components, machining post-machining and chemical polishing are known.The machining of the surface is only possible at readily accessible locations. In addition, the method is very complicated and thus very time-consuming.The surface of the component is removed by the chemical polishing, whereby a material reduction occurs. The material removal is not homogeneous in this case.The object of the invention is to provide a method with which the surface of an additively manufactured, electrically conductive component can be smoothed at inaccessible locations and in a time-saving manner.This object is achieved according to the invention by the features of method claim 1.The advantages of the invention will be described below. The method uses a feeder which is connected at one end to a high frequency power source and which has a feeder terminal for the component at another end. The method further employs a return conductor connected at one end to the high frequency power source and having a return conductor terminal at another end for the device. The high-frequency current source to be used is designed such that a high-frequency current pulse can be emitted which can be adjusted with respect to a frequency, a pulse duration and a voltage level.The current source can apply a high-frequency alternating voltage to the additively manufactured, electrically conductive component, so that the skin effect occurs as a function of the frequency. As a result of a high-frequency alternating current, the surface of the additively manufactured electrically conductive component is predominantly available for charge carrier transport. The frequency is to be selected depending on the material of the additively manufactured component, so that the skin effect is produced. The electrically conductive component produced additively is heated by the high-frequency alternating current. Due to the skin effect, the surface of the additively manufactured, electrically conductive component is predominantly heated. The current intensity and frequency must be selected such that the heating of the surface of the component is so strong that melting of the material on the surface of the component occurs. The effect is enhanced by a rough surface which increases the resistance and leads to further heating and melting of the surface. The surface of the component is smoothed by the melting of the surface. A smooth surface leads to an increased fatigue strength of additively manufactured components. The method enables surface smoothing even at locations which are difficult to access, i.e. when designing additively manufactured components, subsequent processing of the surface no longer has to be taken into account.According to one embodiment of the invention, the surface of the component is fused with a high-frequency current pulse under a vacuum or under a protective gas. The inert gas or vacuum prevents oxidation of the surface.An exemplary embodiment is described in more detail below with reference to the drawings. The following are shown here: FIG. 1 shows an additively manufactured electrically conductive component with a rough surface, in a vacuum chamber, connected to a high-frequency power source. FIG. 2 shows the additively manufactured electrically conductive component with a smoothed surface, still in the vacuum chamber and still connected to a high-frequency power source.FIG. 1 relates to a method for smoothing the surface of an additively manufactured electrically conductive component 10 which is located in a vacuum chamber 20. The additively manufactured electrical component 10 has a feeder terminal 12 on which is connected to the high-frequency current source 30 via a feeder 14. The component further comprises a return conductor connection 11, which is connected to the high-frequency current source 30 via a return conductor 13. Both the frequency and the current intensity can be adjusted via the high-frequency current source 30, so that melting of the surface of the component 10 occurs and the surface is smoothed. The vacuum prevents oxidation of the surface. Prevention of the oxidation is also achieved by the use of a protective gas.The steps of the method are:First, the feeder connection 12 and the return connection 11 are connected to the component 10 in such a way that the feeder connection 12 and the return connection 11 are spaced apart from one another, so that the current travels a long distance through the component and no direct short circuit occurs. The feeder terminal 12 is connected to the high-frequency power source 30 via a feeder 14. Likewise, the return conductor terminal 11 is connected to the high-frequency power source 30 via the return conductor 13. The component can be located in a vacuum chamber 20 or under a protective gas. The component 10 is acted upon with a high-frequency current pulse in such a way that the frequency of the high-frequency current pulse is selected such that the skin effect occurs, which causes the charge carriers which contribute to the current transport to be displaced outwards. The pulse duration and the voltage level of the high-frequency current pulse are set such that the surface of the component 10 at least partially fuses while smoothing the surface.FIG. 2 shows that component 10 receives a smoothed surface after treatment with a radio-frequency current pulse.List of reference characters10 Additive manufactured electrically conductive component 11 Return conductor terminal 12 Supply conductor terminal 13 Return conductor 14 Supply conductor 20 Vacuum chamber 30 High-frequency current source

Claims

Method for smoothing a surface of an additively manufactured, electrically conductive component (10), having the following features: a) the method uses a feeder (14) which is connected at one end to a high-frequency current source (30) and which has at another end a feeder connection (12) for the component (10), b) the method furthermore uses a return conductor (13) which is connected at one end to the high-frequency current source (30) and which has at another end a return conductor connection (11) for the component (10), c) the high-frequency current source (30) to be used is designed such that a high-frequency current pulse can be emitted, which can be adjusted with respect to a frequency, a pulse duration and a voltage level, in such a way that, the steps of the method are: d) connecting the supply connection (12) and the return connection (11) to the component (10) such that the supply connection (12) and the return connection (11) are spaced apart from one another, e) applying a radio-frequency current pulse to the component (10) such that • the frequency of the radio-frequency current pulse is selected such that a skin effect occurs, and • the pulse duration and the voltage level of the radio-frequency current pulse is set such that the surface of the component (10) at least partially melts, smoothing the surface.Method according to Claim 1, in which the melting of the surface of the component (10) takes place with a high-frequency current pulse under a vacuum (20) or under a protective gas.

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