Apparatus and method for plasma electrolytic machining of the conductive surface of a workpiece by an electrolyte jet

Abstract

An apparatus (1) and a method for plasma electrolytic machining of the conductive surface (2) of a workpiece (3) are described, where it is necessary that at least two jet action areas are generated on the surface of the workpiece. The apparatus has an application unit (4) for applying an electrolyte jet to the surface (2), a supply unit (5) for at least temporarily supplying the application unit (4) with the electrolyte necessary for generating the electrolyte jet, at least one electrode (6) that forms a counter electrode with respect to the surface (2) during machining, and at least one electrical energy source (7) for supplying electrical energy to the electrode and the surface during machining, and is configured such that a current flows when there is contact with the electrolyte between the electrode (6) and the surface (2) to be machined.

Description

Technical Field

[0001] The present invention relates to an apparatus and a method for plasma electrolytic machining of a conductive surface of a workpiece. The apparatus has an application unit for applying an electrolyte jet to the workpiece surface, a supply unit for at least temporarily supplying to the application unit the electrolyte necessary for generating the electrolyte jet, and at least one electrode that forms a counter electrode with respect to the surface as a cathode during machining. Further, at least one voltage source is provided for generating the required voltage, and by this voltage source, a voltage can be applied between the electrode and the surface to be machined that is at least partially in contact with the electrolyte during machining of the workpiece surface.

Background Art

[0002] In the case of workpieces made of metal alloys, the target surface properties are usually not obtained in the primary manufacturing step, so subsequent final processing or refining is required. This includes, for example, surface polishing, cleaning, sterilization, texturing and coating, as well as deburring and rounding of the edges of the workpiece. Here, in particular, the method of changing the surface properties by material removal is of extremely important economically and technically. It is known to finish the metal surface by cutting with a geometrically undefined cutting edge, such as grinding or mechanical polishing, which enables low roughness and high gloss. These always assume that a usually rotating tool can access these surfaces, so it is almost impossible to machine elongated, concave contours and internal surfaces. Furthermore, the principle of this method always requires precise adjustment of the relative position of the tool with respect to the surface to be machined. For example, changing the target contour with exchanged or customizable workpieces requires cumbersome adaptation in the NC program in automated process control, which significantly limits flexibility. In contrast, if this is done manually, in complex components, extremely long processing times of about 20 minutes must be expected. Furthermore, since the results are always dependent on the individual capabilities of the co-workers, the reproducibility is significantly limited, and the health risk due to abrasive dust must be expected. In contrast, the similarly known electrochemical polishing methods, in particular electropolishing and electrochemical removal, are characterized by non-affecting material removal. In the case of electrochemical metal processing, the workpiece is processed by anodic dissolution of the metal present on the surface. The corresponding methods are used in various fields of mechanical engineering, such as tool manufacturing in aerospace technology, vehicle manufacturing, medical technology and microsystem technology, as well as in energy facility construction. In this way, almost all metals can be processed. Here, in contrast to machining, this process is not adversely affected by high strength or hardness. In this regard, electrochemical processing is particularly interesting for high-alloy materials such as nickel-based alloys, titanium alloys or hardened materials.Depending on each selected method, problems may arise due to the partially used high-concentration, high-temperature mineral acids that enhance the electrolyte or material removal and speed up the edge rounding. Furthermore, the achievable roughness and achievable gloss only exist typically in the medium requirement range where a roughness value Ra of 0.2 μm can be obtained. Therefore, this method is not particularly suitable for decorative and functional applications that require a high gloss on the surface.

[0003] A special development of known methods for the electrochemical machining of metal workpieces is plasma electrolytic machining of the conductive surface. The plasma electrolytic machining method is a method of changing the state of the workpiece surface that is at least temporarily in contact with the electrolyte by applying a voltage, and this change is realized, promoted, or affected by the formation of plasma near the surface. In particular, plasma electrolytic oxidation is used especially for the formation of wear-resistant peripheral layers on light metals, while in plasma electrolytic polishing, the peripheral layer is changed by material removal. This is carried out using an aqueous solution of salt instead of a high-concentration acid as the electrolyte compared to electrolytic polishing, where typically the workpiece is immersed in such an electrolyte bath and contact-connected as the anode side. By applying a DC voltage of 200 V to 450 V, preferably 230 V to 350 V, the electrolyte in contact with the workpiece evaporates, forming a vapor film surrounding it, and this vapor film pushes the electrolyte solution away from the workpiece surface. The polishing voltage that decreases through the vapor film causes partial ionization and plasma formation. The surface of the workpiece is homogenously smoothed by combining physical removal processes, chemical removal processes, and electrochemical removal processes, and at the same time, impurities are removed from the surface of the workpiece.

[0004] In this way, in an extremely short time, a surface that is particularly smooth and shiny can be generated without using a tool with a constrained shape. Further, it is not necessary to pre-treat each workpiece, or to remove oil or lubricant that may be present on the surface. Further, depending on the material to be processed, a workpiece surface with a suppressed corrosion tendency can be generated by plasma electrolytic machining. Therefore, this method is suitable not only for reducing surface roughness, but also, in particular, for deburring, generating gloss, passivation, cleaning, sterilization, and smoothing the surface profile.

[0005] The plasma polishing equipment described in the superordinate concept is known from the German Patent Specification No. 102006016368 (DE102006016368B4). The above-mentioned equipment is suitable for cleaning and polishing a conductive workpiece surface, and includes an electrolyte container, a housing for the workpiece, and an energy supply unit for providing the voltage required for plasma electrolytic machining. Further, a control unit is provided for monitoring and setting the required current intensity, and this control unit sets the current intensity according to the speed at which the workpiece is immersed in the electrolyte container.

[0006] Known methods for plasma electrolytic treatment of a conductive surface using an electrolyte bath have decisive limitations regarding the geometry of the workpiece that can be processed. First, stable process control requires that the formed and rising gas bubbles in the form of a homogeneous vapor film can flow along the workpiece contour. This is usually not the case for complex components, especially for extremely concave surfaces or contour deepening structures with a high aspect ratio, for example, in the case of holes, hollow spaces, and elongated profiles with small contour intervals. In this case, since there is no stable and method-typical material removal, plasma electrolytic machining often cannot be used in such cases for industrial processes.

[0007] Another disadvantage is that the required current intensity must be provided in proportion to the component surface. Because the underlying principle of operation is typically 0.2 A / cm 2~0.5 A / cm 2 This is because it requires the current density specific to the material and the current density specific to the electrolyte on the surface of the workpiece within the range. Therefore, according to the output provided to the processing equipment in an average industrial plant, there are technical and economic limits regarding the size of the components in this method, and such limits rarely exceed the dimensions of a cube with a side length of 20 cm. Furthermore, the use of the plasma electrolytic machining method is often not economical for large components that require large processing equipment. This is especially the case when only individual surfaces or contours, such as during deburring, are to be processed instead of the entire surface of the component. In this case, usually, due to the overall surface processing inherent in plasma electrolytic polishing in the electrolyte bath, the current demand, investment demand, and processing costs required to meet the surface requirements will double.

[0008] One approach to avoid the limitation of the machinable component size is to shift to a selective method as known from the specification of German Patent Application Publication No. 102014108447 (DE102014108447A1). This document discloses an apparatus for selectively plasma polishing and / or cleaning the conductive surfaces of components, especially thin plates and films. This apparatus has at least one polishing bath provided with the polarity of the cathode, and the electrolyte is supplied to this polishing bath via a pump system. Here, the workpiece with the polarity of the anode is guided through this bath, where insulating strips extending laterally with respect to the workpiece define the surface in contact with the electrolyte, thus creating a polishing bath that acts selectively only. Such a device eliminates the limit of the maximum component size in the method, but in this device, geometrically complex components are still not machinable or are machinable only very limitedly. Furthermore, in such a device, selective processing of individual surfaces away from the overall part defined in one dimension is also not possible.

[0009] For these reasons, a special plasma electrolytic machining method, so-called jet plasma polishing, assumes the use of an electrolyte jet instead of an electrolyte bath. In this case, the electrolyte nozzle that directs the electrolyte jet at the workpiece simultaneously forms the cathode. Material removal only occurs at the location where the electrolyte jet impinges on the workpiece surface. As a result, the maximum required current intensity is limited, and the machining can be concentrated on the selected locations.

[0010] Equipment for implementing the above method is known from the German Utility Model Specification No. DE202019001138U1. This document describes equipment for plasma polishing the conductive surface of a workpiece. Here, this equipment has a holding fixture for holding the workpiece and an electrolyte container from which the electrolyte is conveyed to a nozzle unit. By means of the nozzle unit, an electrolyte jet is generated that is directed at the surface to be machined for machining the workpiece surface. The electrolyte jet may be directed at the workpiece as a free jet outside the electrolyte bath and used for plasma electrolytic machining (jet plasma polishing), or it may be positioned within the electrolyte container itself. In the latter case, as is known from the prior art, the machining of the workpiece is carried out in an electrolyte bath (bath plasma polishing), where the flow of the electrolyte directed at the surface of the workpiece affects the formation of the vapor film and thus the process control as desired.

[0011] The disadvantage of the described equipment is that only a relatively small area of the workpiece surface is machined, so it takes a long time to machine a relatively large surface, and the machining of complex contours cannot be carried out satisfactorily.

Prior Art Documents

Patent Documents

[0012]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0013] Starting from an apparatus and method for plasma electrolytic machining of a workpiece surface known from the prior art, the object of the present invention is to present a technical solution that can appropriately plasma electrolytic machine relatively large surfaces and / or variously different complex contours. In particular, it is desirable that a high-quality surface can be generated quickly, reliably, and reproducibly even in workpieces having variously different geometries and / or complex surface contours. Also, it is desirable that deburring of relatively large components can be meaningfully achieved taking into account both technical and economic peripheral conditions.

[0014] The technical solution presented is generally suitable for use in industrial processes, especially in mass production, and it is desirable that it can be economically meaningfully integrated into industrial production using relatively simple means. Furthermore, the technical solution presented is suitable for being adaptable to various different processing tasks, especially the processing of workpieces formed in variously different shapes, without requiring significant design effort. Furthermore, a processing facility that can be efficiently manufactured and operated should be presented considering known design principles and from an economic perspective. Here, it is desirable to minimize the energy requirement necessary for plasma electrolytic machining of workpieces having workpiece surfaces of various different shapes, and furthermore, to be able to limit the current intensity peak as easily as possible.

Means for Solving the Problems

[0015] The above problems are solved by the apparatus according to claim 1 and the method according to claim 13. Advantageous embodiments of the present invention are the subject matter of the dependent claims and will be described in detail hereinafter with partial reference to the drawings.

[0016] The present invention relates to an apparatus for electrolytically processing the surface of a workpiece, particularly the conductivity of a workpiece, especially a metal. The apparatus has an application unit for applying an electrolyte jet to the surface, a supply unit for supplying at least temporarily to the application unit the electrolyte necessary for generating the electrolyte jet, at least one electrode for forming a counter electrode, particularly a cathode, with respect to the surface during processing, and at least one unit capable of supplying electrical energy to the electrode and the surface during processing such that a current flows when in contact with the electrolyte between the electrode and the surface to be processed. According to the present invention, the apparatus is characterized in that the application unit is configured to generate a first electrolyte jet having various different jet shapes, jet directions, jet action regions, arrangements in space, jet compositions and / or flow characteristics, and at least one second electrolyte jet separate from the first electrolyte jet, and to apply the first electrolyte jet and the at least one second electrolyte jet to the surface of the workpiece simultaneously or sequentially. Thus, the essential idea of the present invention is based on providing an application unit capable of applying at least two jets having various different characteristics, particularly from various different directions and having various different action regions, simultaneously or sequentially to the surface of the workpiece to be processed. In this connection, the jet action region is to be understood as the region of the surface of the workpiece to be processed where the electrolyte jet impinges and at least one surface characteristic in this region changes at least partially. What is important here is that the surface of the workpiece is processed using at least two electrolyte jets simultaneously or sequentially, and these electrolyte jets differ with respect to at least one characteristic, their orientation, their arrangement in space, and / or the jet action region on which the at least two electrolyte jets act. The at least two electrolyte jets first generated by the application unit preferably flow out from different outflow openings of the application unit and are not mixed on the flow path between the application unit and the jet action region on the surface of the workpiece to be treated, and are in particular separate jets that are not mixed into one homogeneous jet.Particularly preferably, at least two separate electrolyte jets impinge on non-overlapping or only partially overlapping jet action areas on the workpiece surface. Thus, these separate electrolyte jets generated in accordance with the present invention have the characteristic that they are always independent jets, and their characteristics can be set as required, as compared to splitting the flow into individual linear flows such as those caused by a perforated plate or an aerator. In contrast, a jet can be separated into different linear flows by a perforated plate or an aerator for only a short time, but these linear flows merge again after passing through a flow obstacle in the form of a perforated plate or an aerator to form a single common jet. In contrast, according to the present invention, at least two electrolyte jets are generated and are directed towards the workpiece surface, so that at least partially different jet action areas on the workpiece surface can also be machined. The important thing here is that the characteristics of at least two separate electrolyte jets can be set to be different from each other, so that, particularly as required, workpieces with complex surface contours can be machined.

[0017] In a particular embodiment, at least two electrolyte jets are directed, or should be directed, such that their projection planes at least partially correspond to the shape and / or contour of the surface to be machined. Machining is understood, in the context of the present invention, to be the removal of surface material, cleaning, the alteration of at least one property of the surface layer and / or the application of material to the surface, in particular polishing, deburring, oxidation, degreasing and / or defatting. With regard to the supply unit, it is advantageous if the supply unit has at least one conveying element in the form of, for example, a spiral pump, an impeller pump or a gear pump, which conveying element enables at least substantially pulsation-free conveyance of the electrolyte to the application unit. This is advantageous because pulsation of the electrolyte jet applied to the workpiece surface impairs the stable formation of a vapor film on the workpiece surface.

[0018] In this context, it is generally assumed that the device is a stationary device or a transportable device for appropriately processing the surface of a conductive material, especially a metal. Therefore, it is assumed that the equipment is formed as a stationary machine tool for processing the workpiece surface, or is formed as a transportable, preferably manually guidable machine tool that is transported to the workpiece to be processed each time. Therefore, by using the technical solution according to the present invention, it is possible to relatively easily, preferably automatically, perform plasma electrolytic machining, especially polishing, and / or deburring of a given contour of the conductive workpiece surface. Based on the flexible configuration of the device according to the present invention, in three-dimensional space, a plurality of electrolyte jets having different characteristics can be applied to the surface to be processed simultaneously or at time intervals from each other.

[0019] According to a preferred embodiment, in this case, the application unit is configured such that at least two electrolyte jets can be applied to the workpiece surface to be processed from different directions simultaneously or at time intervals. Preferably, the application unit has at least two outflow openings, especially nozzles, in this case, and through these outflow openings, the electrolyte jets can be applied to the workpiece surface to be processed as desired. These outflow openings are preferably arranged or should be arranged so that at least one of the plurality of electrolyte jets can be applied at a process-specific angle to a surface having various different contours for surface machining. This angle should preferably be selected such that the electrolyte jet is directed along the surface normal or the contour normal. However, in particular, it may also be advantageous to select a deviated angle based on accessibility, the geometry of the surface, or the machining purpose. In this context, it is assumed that the entire application unit and / or the individual outflow openings are moved as desired.

[0020] In a special development form of the present invention, it is assumed that the application unit has at least one adjustment element that can change the jet shape, jet direction, jet action area, jet composition and / or flow characteristics of the electrolyte jet. Therefore, such an adjustment element ensures that the electrolyte jet can be applied to the surface of the workpiece with different characteristics and adapted to each demand or each processing task. In this regard, it is assumed that such an adjustment element is configured to change the outflow opening, especially the size, shape and / or orientation of the nozzle as required. Therefore, generally, it is assumed that the orientation, jet shape, flow velocity and / or volume flow rate of the electrolyte jet are changed using such an outflow opening. At least a temporary interruption or pulsating application of at least one of the plurality of electrolyte jets is also assumed.

[0021] Alternatively or additionally, it is assumed that the adjustment element has at least one valve and / or metering unit, and the composition of the electrolyte jet applied by the application unit can be changed by this valve and / or metering unit. In order to appropriately adapt the flow characteristics and / or temperature of the electrolyte to the requirements of each processing task imposed as expected, it is also assumed that the adjustment element has at least one actuator, mixing element and / or heating element. For plasma polishing, an electrolyte temperature of 60°C to 95°C is preferred. This is because the energy to be introduced until the evaporation of the electrolyte is reduced thereby. This can be realized, for example, by a screw-in heating device, a through-flow heating device, a ceramic heating device or a combination thereof. In contrast, plasma electrolytic oxidation is possible using an electrolyte at room temperature, for example.

[0022] In a further special configuration of the present invention, at least one measurement unit is provided in order to continuously or intermittently measure at least one property of the surface, to determine the distance between the application unit and / or the outflow opening of the application unit and the surface, and / or to determine the relative position of the application unit with respect to the surface. Furthermore, preferably, at least one control unit is provided, by which a control signal can be generated according to the properties of the workpiece surface, the measured values generated by the measurement unit and / or the target values, and the jet shape, jet direction, jet action area, jet composition, arrangement of the electrolyte jet in space, activation or deactivation of at least one electrolyte jet, and / or the flow characteristics of at least one of the plurality of electrolyte jets of the electrolyte jet can be changed, and can be transmitted to the application unit. Therefore, such a control unit, which is advantageously freely programmable, enables particularly flexible use of the device configured according to the present invention. The control unit is preferably configured such that the required individual process parameters, for example, the temperature, flow shape, flow velocity, volume flow rate and / or composition of at least one of the plurality of electrolyte jets can be changed as required. Alternatively or additionally, it is assumed that the control unit is configured to change the voltage applied between the electrode and the workpiece surface as required, in particular to set the voltage to a value above or below the limit value. Advantageously, the limit value is selected such that plasma electrolytic machining of the workpiece surface is performed under a voltage exceeding the limit value, and electrochemical machining of the workpiece surface is performed under a voltage below the limit value. Therefore, for example, the roughness can first be electrochemically reduced at a high removal rate, and then by changing the voltage, a high-value glossy surface can be generated in a plasma electrolyte manner.

[0023] The combination of such a control unit and at least one of the adjustment elements described above is particularly advantageous, by means of which it is possible to generate at least two electrolyte jets having different properties and apply them to the workpiece surface to be machined, particularly flexibly and effectively, and / or to change the mode of surface machining by changing the voltage.

[0024] In a further special configuration of the invention, this configuration has at least one measuring unit for continuously or intermittently measuring at least one property of the workpiece surface, in particular the surface roughness, and / or for continuously or intermittently determining the relative position of the application unit with respect to the surface. In an advantageous configuration, the measuring unit is directed towards the jet action area. Alternatively or additionally thereto, in particular when the application unit is relatively moved with respect to the workpiece surface as prescribed, it is expedient to provide at least two measuring units, which detect at least one area in front of the jet action area and at least one area behind the jet action area. The properties of the surface can be detected, in particular optically, for example by means of gloss measurement via a camera or by laser-based recording of the roughness profile. Furthermore, measurement via ultrasound in particular is also envisaged for determining the relative position.

[0025] It is particularly advantageous to combine such a measuring unit with at least one of the control units described above and one of the adjustment elements described above, by means of which the measurement results can be directly used for controlling the machining process. Thus, for example, the relative speed of the application unit with respect to the surface, the machining voltage or the jet composition of the electrolyte can be changed in accordance with the comparison of the measurement by the measuring unit with the target state. Furthermore, such an arrangement enables continuous recording of data for the purpose of effective quality assurance.

[0026] According to a particularly suitable further embodiment of the invention, the application unit has at least two outflow openings, in particular two nozzle elements, for applying the electrolyte jet. Preferably, these outflow openings and / or the elements forming these outflow openings are movably arranged, dimensioned differently, the electrolyte can be supplied separately from the supply unit, and / or at least two electrolyte jets having different jet shapes and / or flow characteristics are configured to be applied onto the workpiece surface.

[0027] The application unit can be flexibly adapted according to the invention to each machining task. Nevertheless, it can also be adapted to the imposed requirements, in particular to the material to be machined and the surface contour, by means of relatively simple means. In this case, furthermore, it is generally assumed that suitable positioning fixtures and / or moving fixtures are provided to cause a relative movement between the workpiece surface to be machined and at least one outflow opening for the application unit, in particular for the electrolyte jet. The corresponding relative movement can be initiated, for example, selectively by moving the workpiece whose surface is to be machined and / or by moving at least partially the application unit.

[0028] In a further special configuration of the invention, it is assumed that at least part of the application unit and / or in particular of the supply unit for capturing the electrolyte already applied to the workpiece is arranged on at least one robotic arm. In this way, by using an industrial robot, the application unit can be moved particularly flexibly relative to the workpiece surface to be machined. Alternatively, the use of an axis movement mechanism is also possible.

[0029] According to a special development form of the present invention, at least one position adjustment unit is provided to change the distance between the surface of the workpiece to be machined and at least one outflow opening of the application unit, and / or to change the relative arrangement between at least one outflow opening of the application unit and the surface of the workpiece to be machined. Advantageously, appropriate movement of the application unit and / or the workpiece can be initiated by a robotic arm and / or an axis movement mechanism. Thus, by such a position adjustment unit, the size of the gap to be overcome by at least one electrolyte jet between at least one outflow opening among a plurality of outflow openings and the surface to be machined can be set as desired. In this way, not only the force with which the electrolyte jet impinges on the workpiece surface and thus affects the formation of the vapor film, but also the polishing current generated at a predetermined voltage and the voltage required for the generation of the required polishing current can be set as desired. Regarding the geometric accuracy of the jet shape with respect to the outflow opening, in particular in the case of an electrolyte jet that does not extend along gravity, a short distance is advantageous. However, in this case, care must be taken to avoid the shortest distance in order to prevent spark flashover.

[0030] According to a further special configuration of the present invention, it is assumed that the polishing current flowing during the machining of the workpiece surface is measured. In this case, the corresponding measured value can be used to control or adjust the machining process in an appropriate manner. In a special development form, in this regard, it is assumed that when the measured current intensity of the polishing current corresponds to a target value, the process is assumed to be proceeding at least almost error-free. On the other hand, when the current intensity changes significantly temporarily, that is, when the corresponding value repeatedly fluctuates strongly, especially upward, in the direction of a larger value, it is preferably presumed that the vapor film collapses and then a new ignition occurs.

[0031] In this way, quality assurance can be advantageously achieved, and / or the obtained measurement values and / or values derived from these measurement values can be used to change the characteristics of the adjustment elements and / or adjustment means and thus, in turn, to influence the surface treatment process as desired and as required.

[0032] In a further particularly special configuration of the invention, it is assumed that an electrode, preferably a cathode, at least partially surrounds the electrolyte jet. In this case, advantageously, the electrode is configured, for example, as a conductive tube member which surrounds the electrolyte jet in the region of the outflow opening and thus forms the electrode in a suitable manner. In this context, it is assumed that the application unit is configured to be electrically insulating and, during operation, has at least individual conductive regions which form a counter electrode with respect to the workpiece surface to be machined, as the electrode, in particular the cathode. These conductive regions of the application unit are preferably configured as tube members, and at the ends of these tube members there are provided respective outflow openings for the outflow of the electrolyte jet. During the machining process, it is assumed that the electric field and thus the region of the workpiece surface to be machined is changed by switching on and off the conductive regions provided in the application unit as desired. Similarly, it is also assumed that the entire application unit is configured to be conductive and forms the electrode of the device according to the invention during the machining process. In this case, the number and configuration of the electrodes should always be considered such that the cathode area should be larger than the anode area for the safe and stable operation of the plasma polishing equipment, and here a ratio of at least 5:1 is preferred.

[0033] According to an alternative or supplementary embodiment, the flow-through of the electrolyte can be switched on and off, i.e. pulsed, as required, at at least one outflow opening of the application unit.

[0034] In a further special embodiment, it is assumed that the supply of electrical energy to the electrode and the surface to be machined can be varied using at least one adjustment means. In this context, it is assumed that the adjustment means is configured such that the supply of electrical energy is interrupted completely, at least temporarily, or only the current intensity or voltage is changed. Preferably, a DC voltage of 200 V to 450 V is applied between the electrode and the surface to be machined. In this way, the workpiece surface can be polished and / or deburred particularly suitably. When the voltage drops to a value of, for example, 120 V, the workpiece surface is no longer machined by plasma electrolysis, but rather electrochemically. In the case of electrochemical machining, the material removal per unit time on the workpiece surface increases, so that by changing the voltage, the type of machining, in particular the magnitude or rate of material removal, can be varied as desired.

[0035] According to a special embodiment of the invention, the supply unit has an electrolyte supply section for supplying an electrolyte to the application unit, an electrolyte discharge section for discharging at least partially the electrolyte applied by the application unit, and a purification unit capable of changing at least one characteristic of the discharged electrolyte, in particular the temperature, pH value, conductivity and / or turbidity. The supply unit according to this embodiment is advantageously configured such that the electrolyte is first applied by the application unit to the workpiece surface to be machined, then captured and advantageously purified again, whereby the electrolyte can be reused for machining the workpiece surface. Preferably, the electrolyte discharge section has a blower unit, a compressed air unit and / or a suction section, whereby the electrolyte is sucked and / or blown away after impinging on the surface to be machined. Preferably, the electrolyte impinging on the surface is sucked or blown away as desired and discharged via the discharge section, such that in some cases the electrolyte can be reused after purification. In this way, in the peripheral region, the occurrence of a removal phenomenon outside the defined working surface is prevented.

[0036] In this context, it is advantageous that at least one sensor unit is provided which is capable of detecting at least one property of the electrolyte, in particular conductivity, pH value, turbidity and / or temperature. In this way, for example, it is envisaged that the salt content of the electrolyte used is measured via conductivity measurement and, if necessary, raised again to the required amount using a suitable metering unit. Similarly, it is possible to introduce further measures, which can be, for example, the appropriate metering supply of at least one pH regulator and / or the cleaning of the electrolyte using suitable filter elements such as, for example, a cyclone separator, a filter, or the metering supply of a chemically active substance.

[0037] By means of electrolyte purification, utilization of the electrolyte over a relatively long period of time and thus a particularly economical operation of the device according to the invention can be achieved. In this context, it is advantageous that the device according to the invention has a container for storing the substances required for metering supply and / or cleaning. Alternatively or additionally, a cleaning unit is provided which enables cleaning of the application unit and / or the outflow opening, where the cleaning is preferably carried out immediately when the electrolyte is exchanged.

[0038] In a further embodiment of the invention, the apparatus comprises at least one emitter, by means of which at least temporarily sound waves and / or electromagnetic waves can be input into at least one of the plurality of electrolyte jets. With such an emitter, sound waves and / or electromagnetic waves can be input into at least one electrolyte jet, whereby in particular the machining of the workpiece surface can be changed, or an additional force input to the surface can be caused. Thus, a corresponding action on the surface can be effected by sound waves, in particular to influence the formation of the vapor film, or by means of suitable electromagnetic radiation, for example high-energy laser radiation. Similarly, it is envisaged that a light beam having a specific color is input into at least one of the plurality of electrolyte jets, for example using an LED, in order to indicate, for example, the application of the machining voltage and the presence of the corresponding danger during contact with the operator. Thus, the corresponding light beam input into at least one electrolyte jet may well be a warning indication for the user and advantageously forms part of a special safety device.

[0039] According to a special embodiment of the invention, it is envisaged that the device according to the invention is combined with other components, in particular in order to enable an effective integration into an industrial manufacturing process with maintenance-free operation over as long a period as possible. In a special configuration, an electrolyte concentrate container for storing at least one concentrate is provided, where, by mixing this concentrate with water, preferably deionized water, an electrolyte ready for use is advantageously produced. The corresponding production can preferably be carried out automatically. Similarly, it is also envisaged to supplement the corresponding production process by the above purification process. Here, the equipment for purification, which is preferably carried out continuously, may likewise be of a special configuration and may in particular be a filter installation for suspended particles, in particular provided with a cyclone filter, a metering unit for metering the precipitant and / or an electrolytic cell.

[0040] Alternatively or additionally, a container for storing a pH regulator may be provided, thereby enabling the metering unit to acidify the electrolyte during the process. Further, a storage container for at least one cleaning agent is provided, whereby preferably automatically, it is envisaged that the application unit, in particular at least one outflow opening, is cleaned. Preferably, cleaning is carried out when the electrolyte is exchanged.

[0041] In a special configuration of the present invention, elements for moving the workpiece to be machined are provided before, after or during the machining of the workpiece surface, and these elements simultaneously enable the transmission of electrical energy to the workpiece surface to be machined. Such moving means may be configured, for example, as rollers pressed against the workpiece with appropriate pressure. Further, it is envisaged that the transmission of electrical energy to the workpiece moved relative to the application unit is realized by frictional contact.

[0042] According to a special development of the present invention, at least one unit is provided which can introduce air and / or at least one kind of gas into at least one of the plurality of electrolyte jets, at least temporarily. Bubbles of air or gas in the electrolyte jet generally promote the formation of a vapor film on the workpiece surface to be machined, which is advantageous. Preferably, the unit for introducing air and / or gas into the electrolyte jet has at least one suitable jet regulator. In this context, at least one outflow opening of the application unit has an exchangeable insert, and it is envisaged that the injection or suction of air and / or gas into the electrolyte jet in the region of the outflow opening is at least promoted through this insert. Alternatively, at least one of the plurality of outflow openings has a suitable internal structure, in particular a surface structure, which enables a suitable supply of air and / or gas to the electrolyte jet and / or the formation of bubbles of air and / or gas in the electrolyte jet.

[0043] Furthermore, in the region of at least one outflow opening among the plurality of outflow openings of the application unit, an electrically insulating spacer is provided, and this spacer at least partially surrounds the electrolyte jet, whereby it is assumed that the effective outflow opening of the free jet is moved closer in the direction of the workpiece surface. The remaining gap may be reduced to zero, whereby the spacer forms a direct, electrically insulating connection to the workpiece surface. Preferably, such a spacer is at least partially formed in a tubular shape, whereby the electrolyte jet impinges on the workpiece surface to be machined through such a spacer. Thereby, the intended application of the electrolyte jet, which can reduce the distance to be overcome by the free jet to zero, is carried out.

[0044] In a further configuration of the present invention, at least one outflow opening of the application unit has a surface structure inside itself that is suitable for forming the desired flow shape of the electrolyte jet. Furthermore, in this context, it is assumed that the effective cathode surface area is enlarged based on the structured surface in the region of the outflow opening. As the surface structure, in this case, for example, deterministic structures such as meshes, gratings, and / or tubular texturing, as well as probabilistic structures in the form of, for example, sintered structures and / or sponge-like structures, are also assumed. Preferably, these surface structures selected according to each machining task may be installable in the outflow opening of the application unit in the form of replaceable inserts.

[0045] Furthermore, in order to supply electrical energy to the device according to the invention, it is advantageous to use an accumulator unit such as a storage battery or a capacitor, in particular a supercapacitor. In this way, in particular, the peak load of the current intensity that can occur during the ignition process at the start of the machining can be minimized. Through such an accumulator for electrical energy, the corresponding peak load can be at least partially reduced. In this way, the power consumption of the device according to the invention is decoupled from the power output of the provided power supply network. By using at least one of the plurality of electrical accumulators described above, an unacceptable load on the current network of the industrial plant can be eliminated, thereby ensuring the safe and continuous operation of the device according to the invention. Furthermore, it is envisaged that the accumulator element is configured such that the current intensity provided by this accumulator element can be maintained over a relatively long period of time, in particular over the machining duration of the workpiece. In this way, for example, a facility that is limited to a machining current of 150 A based on the connected load can be used to machine a workpiece that requires a machining current of 200 A with a corresponding charge.

[0046] In addition to the device, the present invention also relates to a method for electrochemically machining the conductivity of a workpiece, in particular the surface of a metal, wherein at least one electrolyte is conveyed to an application unit, via which an electrolyte jet is applied at least temporarily to the surface of the workpiece, and a voltage is applied between the surface of the workpiece to be machined and an electrode that is at least partially in contact with the electrolyte, whereby the electrode forms, during machining, a counter electrode, in particular a cathode, with respect to the surface of the workpiece, which is preferably an anode. The method according to the invention is characterized in that a first electrolyte jet and at least one second electrolyte jet having different jet shapes, jet directions, jet action areas, jet compositions and / or flow characteristics are applied to the surface of the workpiece via the application unit simultaneously or successively. Thus, the method according to the invention is characterized in that the surface of the workpiece to be machined is machined simultaneously or successively using electrolyte jets having different properties. During machining, material removal, surface cleaning, modification of at least one surface property and / or material application are likewise carried out. The electrolyte jet is preferably applied in the direction of the surface of the workpiece to be machined, preferably from one of a plurality of movable outflow openings.

[0047] At least two electrolyte jets that are first generated by or within the application unit are separate jets, which are preferably applied from different outflow openings of the application unit and are not mixed in the flow path between the application unit and the jet action area on the workpiece surface to be processed, and in particular are not mixed into a homogeneous jet. Particularly preferably, the at least two separate electrolyte jets impinge on non-overlapping or only partially overlapping jet action areas on the workpiece surface. Thus, these separate electrolyte jets generated in accordance with the present invention have the characteristic that, compared to dividing the flow into individual linear flows such as those caused by a perforated plate or an aerator, they are always independent jets and their characteristics can be set as required. In contrast, a jet can be separated into different linear flows by a perforated plate or an aerator for only a short time, and these linear flows rejoin after flowing through the flow obstacle in the form of a perforated plate or an aerator to form one common jet. Different from this, according to the present invention, at least two electrolyte jets are generated and are directed towards the workpiece surface, so that at least partially different jet action areas on the workpiece surface can also be processed. What is important here is that the characteristics of the at least two separate electrolyte jets can be set differently from each other, so that even a workpiece with a complex surface contour can be processed particularly as required.

[0048] According to a special embodiment of the present invention, electrolyte jets deflected towards the surface from various different directions are applied to the surface to be processed. Each electrolyte jet can be interrupted as required and / or the characteristics of the electrolyte jet can be changed.

[0049] Furthermore, it is advantageous to move the surface of the workpiece to be machined relative to the application unit. The relative movement can here be effected, selectively, by moving a plurality of application units or at least one of the plurality of application units and / or the workpiece. Thus, by the method according to the invention, it is possible to machine, for example deburr, a workpiece having a relatively complex geometry and surface contour such that a surface having a relatively high surface quality is produced, in particular when using an application unit having a plurality of outflow openings, in particular nozzles.

[0050] In a special embodiment of the invention, the electrolyte is at least partially captured after being applied onto the surface of the workpiece, the captured electrolyte is purified by changing at least one property thereof, and in the purified state is reapplied onto the surface of the workpiece. According to this embodiment, the electrolyte is conveyed in a cyclic manner, where a temporary storage in a tank is envisaged. In this way, particularly effective machining of the workpiece surface is made possible based on the use of the electrolyte over a relatively long period. Furthermore, substances required for the purification and / or cleaning of the electrolyte are stored in a suitable container and, if required, are metered in, preferably using suitable control or regulation, in particular to increase the salt content and / or to lower the pH value.

[0051] According to a particularly special development form of the present invention, the configuration of the application unit, in particular the shape of the application unit, the arrangement of at least one outflow opening, and / or the adjustment element for changing at least one characteristic of the electrolyte jet are such that the outer contour of the application unit and / or the projection surface of the applied electrolyte jet are configured to at least substantially completely reproduce the shape of the surface to be machined of the workpiece. Here, advantageously, it is assumed that the application unit is arranged in a fixed position, for example on a machine frame, and the workpiece to be machined is inserted automatically or semi-automatically. After the workpiece whose surface is to be machined is positioned, in this case, preferably the supply unit, the application unit and the voltage source are operated, whereby a plurality of electrolyte jets are applied to the surface to be machined simultaneously or sequentially, and a voltage is applied between the electrode and the workpiece surface. Based on the formation of a partially ionized gas envelope, plasma is stabilized on the surface of the workpiece, and the desired machining, in particular material removal, is performed.

[0052] Similarly, it is also assumed that the application unit and / or the individual application openings are at least temporarily moved relative to the workpiece. Therefore, after the workpiece is inserted, it is assumed that they are first moved to the machining position and returned to the initial state after the machining process is completed. Furthermore, continuous machining of the workpiece is assumed, in which the workpiece and at least part of the application unit, such as individual outflow openings, are also moved. Generally, continuous machining of the workpiece, for example by moving the workpiece, as well as machining in a plurality of separate steps are assumed. Such a division into separate processing steps can preferably be carried out such that these separate processing steps have as equal power requirements as possible and the current network is loaded as evenly as possible in this way.

[0053] Furthermore, in particular, in order to enable the realization of an optimal process in view of economic manufacturing, it is assumed that the electrolyte supply and / or the energy supply for generating the voltage are at least temporarily interrupted between individual machining steps.

[0054] Advantageously, the device according to the invention and the method according to the invention can be used to deburr metal workpieces. Alternatively or additionally, it is envisaged that the workpiece surface is polished, sterilized and / or cleaned by the solution according to the invention. Furthermore, by using a suitable electrolyte and in particular by setting suitable process parameters with respect to the voltage applied between the electrode and the workpiece surface, plasma electrolytic oxidation (PEO) is envisaged to occur on the workpiece surface to be processed. By such a method, it is possible to produce, for example, a particularly hard wear-resistant peripheral layer such as aluminum and magnesium, and / or a plasma electrolytic coating of the workpiece surface can be realized.

[0055] Preferably, during plasma electrolytic oxidation, a voltage of about 200 V is applied between the electrode and the workpiece surface to be processed. In this connection, in a first step, the workpiece is processed by using a first electrolyte and a first voltage profile in order to cause the desired material removal from the surface to be processed, and subsequently in a second process step, plasma electrolytic coating or plasma electrolytic oxidation (PEO) is carried out by using a second electrolyte and a second voltage profile. When using a suitably formed control unit and / or when using an adjustment element that can be driven and controlled as desired by the control unit, the two-step or multi-step process carried out as described above is carried out by one application unit or by using at least two application units, where it is envisaged that material is removed by one application unit and material is applied or changed by the other application unit.

[0056] Furthermore, it is contemplated that the method according to the invention is carried out such that the conductivity, in particular the surface of the metal, is not only deburred and / or polished, but also subsequent material removal is achieved. In such a case, in the additively manufactured metal component, the machining of the workpiece surface is carried out over a relatively long period of time, as is usually required, for example, to form a rounding in the region of the contour of the workpiece or to smooth the surface profile. Preferably, for this purpose, the residence time of the outflow opening above the region of the workpiece surface to be machined is extended and / or the voltage is reduced for a short time. This reduces the action on the workpiece surface caused by the plasma electrolytic machining, shifts the principle of action for the electrochemical machining of the surface, which is similarly accompanied by a significantly high material removal rate.

[0057] Furthermore, it is contemplated to increase the flow rate of the electrolyte and / or to change the flow shape, i.e., in particular to change the laminar flow to a turbulent flow. In this case, the thickness of the gas layer or vapor layer present on the workpiece surface is reduced or the formation and flow thereof are modified. According to a special development of the invention, air and / or gas is blown into the electrolyte jet to generate a turbulent flow of the electrolyte jet along the workpiece surface, thereby promoting the formation of a gas-plasma envelope. In this context, a controlled or regulated injection and suction of air and / or gas into at least one of the plurality of electrolyte jets is contemplated.

[0058] Furthermore, it is envisaged that at the very start of the machining process, at least one electrolyte jet having a relatively low flow rate is deflected onto the workpiece surface, and in the next process step the flow rate is increased to the normal operating level. In this case, the corresponding change in the flow rate of at least one electrolyte jet can be effected regardless of the number, shape and size of the outflow openings of the application unit. Furthermore, at the start of the working process, i.e. during so-called ignition and during the generation of the plasma on the workpiece surface to be machined, it is advantageous to apply an ignition voltage different from the operating voltage between the electrode and the workpiece surface to be machined and / or to promote the ignition process by an increased or decreased addition of air and / or gas to the electrolyte jet.

[0059] In a special development of the invention, at least one of the plurality of electrolyte jets is not directed as a free electrolyte jet towards the surface of the workpiece, but rather a non-conductive spacer is arranged between the outflow opening of the application unit and the workpiece surface. Such a spacer is preferably formed from ceramic, plastic and / or glass.

[0060] In a special embodiment, the machining of the surface of the workpiece is preferably carried out by the method according to the invention using a stationary application unit which is part of a quick clamping device, where the required machining position of the surface to be machined relative to the application unit is already set and the required electrical contact connection is formed after the workpiece to be machined has been properly fixed.

[0061] Similarly, it is also envisioned to initiate a continuous or timing-controlled relative movement between the workpiece to be machined and the application unit by appropriately moving the application unit and / or the workpiece. In this context, the feed movement of the workpiece is realized at least temporarily using a roller system, where these rollers are advantageously simultaneously conductive and are assumed to enable the transmission of electrical energy to the surface of the workpiece to be machined. Alternatively, it is assumed that an appropriate rubbing contact is provided to transmit electrical energy to the surface of the workpiece to be machined.

[0062] Furthermore, in a special configuration of the present invention, during and / or after machining the workpiece surface and / or during individual machining steps by material removal, material modification or material application, preferably at least one cleaning step, drying step and / or inspection step is preferably automatically carried out, particularly using a camera. The cleaning is preferably carried out using deionized water and / or ethanol.

[0063] In a further special embodiment of the method according to the invention, the workpiece is preheated before machining in order to reduce the temperature difference with respect to the electrolyte and to ensure as constant process conditions as possible throughout the machining time. This is preferably carried out in a temperature-regulated fluid, which may also be the electrolyte itself. Furthermore, it is also envisioned to preheat the workpiece, for example, via induction, particularly via an infrared radiator in the case of selective machining of individual surfaces.

[0064] In a further special configuration of the present invention, it is assumed that the electrolyte is at least partially captured after application to the workpiece surface and is purified by changing at least one property of the captured electrolyte and is reapplied onto the surface of the workpiece in a purified or unpurified state.

[0065] Furthermore, advantageously, before, during, or after the surface machining, at least one machining parameter and / or process parameter, the voltage governing between the electrode and the surface to be machined, the intensity of the current flowing between the electrode and the surface to be machined, the distance between the application unit and / or the outflow opening of the application unit and the workpiece surface, the supply of the electrolyte, the movement of the workpiece, the movement of the application unit, and / or at least one setting of an emitter for inputting sound waves and / or electromagnetic waves into at least one of the plurality of electrolyte jets at least temporarily is / are assumed to be measured and / or adjusted.

[0066] Furthermore, the integration of the method according to the invention into an industrial manufacturing process is advantageously possible when the contour of the workpiece surface to be machined is transmitted directly from a CAD system to a control unit provided therefor for driving and controlling the application unit and / or suitable adjustment elements. By directly delivering the manufacturing data, and thus the geometric contour of the workpiece to be machined, even complex workpiece contours can be machined relatively easily using the method according to the invention, which in particular enables effective deburring and / or polishing of mass-produced workpieces and / or additively manufactured components.

[0067] In order to avoid the load peak of the current intensity when generating the voltage required for plasma electrolytic machining between at least one electrode and the workpiece surface to be machined, it is assumed to use a suitable storage element for accumulating electrical energy, such as a storage battery and / or a capacitor, especially a so-called supercapacitor. By using such an energy storage device, it is possible to buffer the load peak of the current intensity, especially when providing the voltage required during the ignition process. Thereby, the load on the current network of the industrial plant is reduced, and in particular, a safe operation is guaranteed. Finally, it is assumed that the storage element is configured such that the current intensity provided by this storage element can be maintained over a relatively long period, especially over the machining period of the workpiece. In this way, for example, a facility that is limited to a machining current of 150 A based on the connected load can be used to machine a workpiece that requires a machining current of 200 A by appropriate charging.

[0068] In the following, the present invention will be described in detail with reference to the drawings based on specific embodiments without limiting the general inventive concept. The same components are denoted by the same reference numerals in different drawings.

Brief Description of the Drawings

[0069]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0070] Figure 1 schematically shows in a plan view a first embodiment of an apparatus 1 configured according to the present invention for plasma electrolytic machining, preferably deburring and / or polishing, of a surface 2 of a workpiece 3. The illustrated apparatus 1 has a supply unit 5 which supplies an electrolyte required for plasma electrolytic machining of the workpiece surface 2 to an application unit 4. Here, the supply unit 5 has a pump which, during operation, conveys the electrolyte substantially without pulsation from a storage container 16 to a plurality of outflow openings 10 of the application unit 4 in the form of nozzles. The conveyance of the electrolyte is started after the workpiece 3 whose surface 2 is to be machined is fixed in position at the machining position, and a plurality of electrolyte jets impinge on the workpiece surface 2 to be machined from different directions from the individual outflow openings 10. The number, configuration and orientation of the outflow openings 10 through which the electrolyte is applied are selected according to the contour of the workpiece surface 2 to be machined and the machining task. In the embodiment shown in Figure 1, a workpiece 3 pre-manufactured by mechanical mass production is deburred using the apparatus 1 according to the present invention.

[0071] The illustrated apparatus 1 further has, among other things, a control unit 9 by which the supply unit 5 is controlled and both an electrical energy source 7 used as a voltage source and individual adjustment elements 8 of the apparatus 1 are also controlled, and by means of the adjustment elements 8, the application of the electrolyte jets and the characteristics of the electrolyte jets can be set and changed as required. In order to enable appropriate control of the various different elements, a measurement unit 22 is further provided which, in particular for measuring the surface roughness, for continuously or intermittently measuring at least one characteristic of the surface 2, for determining the distance between the application unit 4 and the surface 2, and / or for determining the position and / or orientation of the application unit 4 relative to the surface 2, is equipped with appropriate sensors. The measurement unit 22 and the control unit perform unidirectional or bidirectional data exchange via a data transmission section which may be configured wirelessly and / or wired.

[0072] In this way, during machining, the voltage applied between the electrode 6 of the apparatus 1 and the workpiece surface 2 can be changed, and each outflow opening 10 can be opened and closed as desired. Further, the flow rate and volume flow rate of each electrolyte jet can be changed as required.

[0073] The electrolyte stored in the storage container 16 is preheated by the heating element 18 and then conveyed to the individual outflow openings 10 by a plurality of pumps via the electrolyte supply section 13, so that the electrolyte can be supplied separately to the individual outflow openings 10. The supply of the electrolyte to the outflow openings 10 is further effected via an adjustment element 8, such as a valve, which can change the flow characteristics as desired. Thus, at least two electrolyte jets having different characteristics are applied to the workpiece surface 2 to be machined simultaneously or sequentially via these outflow openings 10.

[0074] During the machining process, a direct voltage of 200 V to 450 V is applied between at least one electrode 6, which is formed by a tube member and whose end forms a respective outlet opening 10, corresponding to the embodiment shown in FIG. 1, and the workpiece surface 2. When the electrolyte jet impinges on the workpiece surface 2 to be machined, gas or steam formation occurs, which leads to the formation of a gas-plasma envelope on the surface 2, under which the desired material removal occurs. After the electrolyte impinges on the workpiece surface 2, it is sucked in by the electrolyte discharge 14 of the supply unit 5 and fed to a purification unit 15 for electrolyte purification. Here, in a first step, suspended particles are removed using a cyclone filter. The turbidity, pH value and conductivity of the discharged electrolyte are then measured by at least one sensor unit 17. If the electrolyte is particularly strongly contaminated, a precipitant is metered from the tank via a metering unit in order to trigger a precipitation reaction in the electrolyte, and the electrolyte is pumped into a separate purification tank. Furthermore, depending on the detected measured values of the conductivity and pH value of the electrolyte, salts, for example ammonium salts and / or pH regulators, if required, are metered in by means of a suitable metering unit 19 from a corresponding storage container. The purified electrolyte then returns to the storage container 16. In the region of the storage container 16, a temperature sensor 20 and a heating element 18 are provided, by means of which the electrolyte is always heated to the required temperature before being fed to the application unit 4 with a number of outlet openings 10.

[0075] According to the embodiment shown in Fig. 1, the machining of the workpiece surface 2 is performed by clamping or clamping the workpiece 3 in the region of the application unit 4 of the device 1, which is configured according to the invention. For its machining, the workpiece 3 is thus inserted into the position reserved for this and fixed in this position. Following this, the individual nozzle-like outlet openings 10 are brought out to their machining position. During the machining of the workpiece surface 2, no relative movement takes place between the application unit 4 and the workpiece 3, whose surface 2 is to be machined, according to the embodiment described herein.

[0076] The individual outflow openings 10 of the application unit 4 and thus the projection surface of the electrolyte jet applied by the application unit 4 exactly reproduce the shape of the surface 2 of the workpiece 3 to be machined. After the machining is completed, the outflow openings 10 are again moved to their rest positions, whereby the distance between the workpiece 3 and the outflow openings 10 increases. Thereafter, the fixing of the workpiece 3 is released and the deburred workpiece is discharged.

[0077] Figure 2 shows a second embodiment of the device 1 according to the invention, in which case the application unit 4 has a movable nozzle head 21 with three outflow openings 10 in the form of nozzles. Through the outflow openings 10, different electrolyte jets can also be applied here, if necessary, to the workpiece surface 2 to be machined. The supply of electrolyte to the individual outflow openings 10, the control of the application unit 4, and the purification of the electrolyte sucked from the workpiece surface 2 are carried out by elements similar to those described in connection with Figure 1.

[0078] However, unlike the embodiment shown in Figure 1, the application unit 4 shown in Figure 2 has outflow openings 10 that are movable relative to the workpiece 3 also during machining, and according to the illustrated embodiment, the three nozzle-shaped outflow openings 10 are moved relative to the workpiece 3 together with the nozzle head 21 as suggested by the arrows.

[0079] The controlled movement of the outflow openings 10 and the application of the electrolyte are carried out in accordance with the contour of the workpiece 3 that is fixed or clamped at its machining position. Here, the movement of the nozzle head 21, the supply of the electrolyte to the individual outflow openings 10, the on / off of the electrodes 6 arranged in the region of the outflow openings 10, and the setting of the voltage applied between the actuated electrode 6 and the workpiece surface 2 to be machined are changed during machining as required, in particular, exactly in accordance with the contour of the surface region to be machined. The outflow openings 10 are likewise formed by the pipe members and their free ends. Here, the individual conductive pipe members assume the function of the electrodes 6, which are counter electrodes, here cathodes, with respect to the anodic workpiece surface 2 during machining. During the machining process, a voltage of 200 V to 450 V is applied between each actuated pipe member and the workpiece surface 2 to be machined. This voltage can be changed during the ignition process at the start of the workpiece machining and also at the start of the electrochemical machining step by a change in the distance between the electrode 6 arranged in the region of the outflow openings 10 and the workpiece surface 2 and / or by the intended positioning of the electrical energy source 7 used as the voltage source.

[0080] Then, during the machining process, the nozzle head 21, together with its nozzle-shaped outflow openings 10, is moved so that the desired contour of the workpiece surface 2 is machined, here deburred.

[0081] In principle, two different types of continuous machining of the workpiece 3 are possible with the device 1 shown in FIG. 2. Thus, the application unit 4 equipped with the nozzle head 21 can be set and positioned so that the outer contour of the workpiece 3 to be machined is accurately or approximately reproduced. As soon as the corresponding positioning is completed, the workpiece 3 is guided along the application unit 4 equipped with the nozzle head 21 and its outflow openings 10. If the individual surface regions of the workpiece 3 guided along the application unit 4 are not to be machined, the application of the electrolyte jet and / or the application of the voltage can be interrupted in this region, in particular via the adjustment means 12.

[0082] In a second possible form of continuous machining, the application unit 4 with the nozzle head 21 shown in FIG. 2 reproduces a general shape, for example a square face, or a hemisphere with a radially directed outflow opening. In this case, it is assumed that the application unit 4 with the movably arranged nozzle head 21 is moved and positioned by a suitable drive element, such as the arm of an industrial robot, in order to move it successively along the surface area to be machined of the workpiece.

Explanation of Signs

[0083] 1 Device for plasma electrolytic machining of a conductive workpiece surface 2 Surface 3 Workpiece 4 Application unit 5 Supply unit 6 Electrode 7 Electrical energy source 8 Adjustment element 9 Control unit 10 Outflow opening 11 Position adjustment unit 12 Adjustment means 13 Electrolyte supply section 14 Electrolyte discharge section 15 Purification unit 16 Storage container 17 Sensor unit 18 Heating element 19 Dosage unit 20 Temperature sensor 21 Nozzle head 22 Measuring unit

Claims

1. An apparatus (1) for plasma electrolytic processing of a conductive surface (2) of a workpiece (3), The apparatus (1) comprises: an application unit (4) for applying an electrolyte jet to the surface (2); a supply unit (5) for at least temporarily supplying the electrolyte necessary to generate the electrolyte jet to the application unit (4); at least one electrode (6) for forming a counter electrode to the surface (2) during the processing; and at least one electrical energy source (7) for supplying electrical energy to the electrode and the surface during the processing so that an electric current flows between the electrode (6) and the surface (2) to be processed when in contact with the electrolyte, The application unit (4) comprises a first electrolyte jet and at least one separate second electrolyte jet having different jetting regions on the surface to be processed, wherein at least one characteristic of the electrolyte jet, selected from the group of characteristics including jet shape, jet direction, jetting region, spatial arrangement, jet composition, and flow characteristics, is adjustable, and each of the electrolyte jets is configured to generate a first electrolyte jet and at least one separate second electrolyte jet that are applied simultaneously or sequentially to the surface (2) of the workpiece (3). Apparatus (1) characterized by the following.

2. The application unit (4) has at least one adjustment element (8) that can change the jet shape, jet direction, jet composition, jet action area, and / or flow characteristics of the electrolyte jet. The apparatus according to claim 1.

3. To continuously or intermittently measure at least one characteristic of the surface (2), to determine the distance between the application unit (4) and the surface (2), and / or to determine the relative position of the application unit (4) with respect to the surface (2), at least one measuring unit (22) is provided, and / or A control unit (9) is provided, and the control unit (9) is capable of generating a control signal according to the characteristics and / or target value of the workpiece surface (2), and is capable of transmitting the control signal to the application unit (4) in order to change the jet shape, jet direction, jet composition, jet working area, arrangement of the electrolyte jet in space, and / or the flow characteristics of the electrolyte jet. The apparatus according to claim 1.

4. The application unit (4) has at least two outlet openings (10). The apparatus according to claim 1.

5. The outflow opening (10) is movable, has different dimensions, is formed in a tubular or nozzle shape, and is configured to allow the electrolyte to be supplied separately from the supply unit, and / or to allow at least two electrolyte jets having different jet shapes, jet operating regions, spatial arrangements, and / or flow characteristics to be applied to the workpiece surface. The apparatus according to claim 4.

6. At least one position adjustment unit (11) is provided to change the distance and / or relative arrangement between the surface (2) of the workpiece (3) and at least one outflow opening (10) of the application unit (4). The apparatus according to claim 1.

7. The electrode (6) at least partially surrounds the electrolyte jet during operation. The apparatus according to claim 1.

8. The supply of electrical energy to the electrode, the voltage governing the relationship between the electrode and the surface to be processed, and / or the strength of the current flowing between the electrode and the surface to be processed can be changed using at least one adjustment means (12). The apparatus according to claim 1.

9. The supply unit (5) includes an electrolyte supply section (13) capable of supplying electrolyte to the application unit (4), an electrolyte discharge section (14) capable of discharging the electrolyte applied by the application unit (4), and / or a purification unit (15) capable of changing at least one characteristic of the discharged electrolyte. The apparatus according to claim 1.

10. At least one sensor unit (17) capable of detecting at least one characteristic of the electrolyte is provided. The apparatus according to claim 1.

11. At least one emitter is provided that can temporarily input sound waves and / or electromagnetic waves to at least one of the plurality of electrolyte jets. The apparatus according to claim 1.

12. A method for plasma electrolytic machining of a conductive surface (2) of a workpiece (3), In a method comprising: transporting at least one electrolyte to an application unit (4); applying an electrolyte jet at least temporarily to the surface (2) of the workpiece (3) by the application unit (4); applying a voltage between the surface (2) of the workpiece (3) to be processed and an electrode (6) that is at least partially in contact with the electrolyte, thereby causing the electrode (6) to form a counter electrode to the surface (2) of the workpiece (3) during processing, A first electrolyte jet and a separate at least one second electrolyte jet having different jet action regions, wherein at least one characteristic of each of the electrolyte jets, selected from the group of characteristics including jet shape, jet direction, jet action region, spatial arrangement, jet composition, and flow characteristics, is adjustable, and the individual electrolyte jets act simultaneously or sequentially on the surface (2) of the workpiece (3) via the application unit (4), the application unit (4) generates the first electrolyte jet and the separate at least one second electrolyte jet. A method characterized by the following:

13. The surface (2) of the workpiece (3) to be processed is moved relative to the application unit (4). The method according to claim 12.

14. The electrolyte is at least partially captured after being applied to the surface (2) of the workpiece (3), purified by changing at least one property of the captured electrolyte, and then reapplied to the surface (2) of the workpiece (3) in either the purified or unpurified state. The method according to claim 12.

15. Before, during, or after machining the surface, at least one machining parameter and / or process parameter, a voltage applied between the electrode (6) and the surface (2) to be machined, the strength of the current flowing between the electrode (6) and the surface (2) to be machined, the distance between the application unit (4) and / or the outlet opening (10) of the application unit (4) and the workpiece surface (2), the supply of electrolyte, the movement of the workpiece (3), the movement of the application unit (4), and / or at least one setting of an emitter that at least temporarily inputs sound waves and / or electromagnetic waves to at least one of the plurality of electrolyte jets, is measured and / or adjusted. The method according to claim 12.

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