EP2266701A1 - Work electrode for an electrodynamic fragmentation assembly - Google Patents

Abstract

The electrode has an insulator body (1) with a central conductor (2) that axially passes through the insulator body. An electrode tip (3) is arranged at a working end of the central conductor, and is formed by a removable interchanging part (4). The electrode tip adjoins a stop area (6) of the central conductor with a contact area (5) under axial compressive prestressing in an axial direction. The interchanging part exhibits an elongation region (8) between a screw connection (7) and the contact area. An independent claim is also included for an interchanging part for a working electrode, comprising a base plate.

Description

TECHNICAL AREA

The invention relates to a working electrode for an electrodynamic fragmentation system, change parts for such a working electrode and a use of the working electrode according to the preambles of the independent claims.

STATE OF THE ART

In the electrodynamic fragmentation of material, such as concrete, high voltage breakdowns are produced by a working electrode applied to high voltage pulses and a base electrode, which is usually at a neutral potential, through the material to be comminuted, which leads to the comminution of the material. In this case, a slight removal of material at the working electrode tip takes place at each high-voltage breakdown, so that it is worn after a certain period of use and must be replaced. It may also be necessary to change the electrode when changing the material to be digested with the equipment in order to prevent contamination of the end product with unwanted electrode material. In both cases, in electrodynamic fragmentation systems with non-exchangeable electrode tips, the entire working electrode including insulator must be replaced, which is a costly and time-consuming endeavor, not least because the working electrodes are usually coupled on their terminal side to a system filled with insulator oil. A further disadvantage results from the fact that it is uneconomical, not completely used electrodes use up, since the installation costs measured relative to the remaining useful life is relatively high.

Furthermore, high-voltage electrodes are known from the prior art in which the electrode tip is formed by an exchangeable exchangeable part and which thereby largely avoid the aforementioned disadvantages. Such high voltage electrodes are for example in SU 1790069 A1 . SU 1781892 A1 . JP 2003 001137 A . US 2005/0150668 A1 . DE 38 44 419 A1 and US 4,458,153 shown. The electrode tip is either screwed to the central conductor of the high voltage electrode or in the case of DE 38 44 419 A1 However, these high-voltage electrodes have the disadvantage that it can come at high pressure pulsations in the working space to a dissolution of the electrode tip forming change part and in the case of the clamped electrode tip also a structurally relatively complex arrangement for fixing the Electrode tip is required.

PRESENTATION OF THE INVENTION

It is therefore the task of providing a working electrode which does not have the disadvantages of the prior art or at least partially avoids it.

This object is achieved by the working electrode and the change parts for such a working electrode according to the independent claims.

Accordingly, a first aspect of the invention relates to a working electrode for an electrodynamic fragmentation system with a replaceable electrode tip. The working electrode comprises an insulator body, for example made of plastic or of a ceramic material, with a central conductor of a highly electrically conductive, preferably metallic material, for example of aluminum, copper or stainless steel, which passes through the insulator axially. At one end of the central conductor is designed for coupling to a high voltage generator for charging the working electrode with high voltage pulses. At its other end, the so-called working end, which dips in operation in the filled with process fluid, eg water, and the material to be crushed workspace of the fragmentation, the central conductor carries an electrode tip, which forms the starting point for the voltage breakdown in operation. The electrode tip is formed by a replaceable, one-piece or multi-part removable part.

The removable part is frictionally secured by clamping in an end opening in the working end of the central conductor, which is preferably accomplished by the replacement part comprises a preferably cylindrical expansion sleeve and an at least partially arranged in the expansion sleeve expansion means by which the expansion sleeve in such a spreadable area is that it is pressed radially against the wall of the frontal opening and thereby clamped axially immovable in the opening. As a result, a secure attachment of the removable part can be achieved at the central conductor in a simple manner. Also, such working electrodes have the advantage that when a wear of the electrode or a change in the material to be crushed, only the electrode tip must be changed and, for example, an opening of an oil-filled high-voltage system for the purpose of replacing the entire working electrode is superfluous. It is thereby advantageous to significantly reduce the maintenance-related downtime and operating costs of electrodynamic fragmentation systems. It is advantageous if the expansion body is connected to a drive element for axially displacing it with respect to the expansion sleeve to effect a radial spreading of the expansion sleeve, which protrudes at the working end of the central conductor emerges from the frontal opening and at its end facing away from the spreader end forms the electrode tip. As a result, the clamping of the removable part in the central conductor can be effected in a simple manner by exerting an axial force on the drive element. If, in addition, the expansion body and the drive element are formed integrally with one another, which is preferred, the result is a particularly simple and robust construction.

It is also preferred if the expansion body has a preferably cone-shaped or pyramid-shaped section for radial spreading of the expansion sleeve or is formed overall as a cone or truncated pyramid, as this very large expansion forces can be generated in a controlled manner.

Advantageously, the drive element wipe the electrode tip and the spreader on an external thread, by means of which an axial force can be exerted on this to effect a displacement of the spreader and a resulting radial expansion and clamping of the expansion in the opening in the central conductor. In this way, relatively large displacement forces can be provided in a controlled manner.

In this case, the expansion body is designed such that an axial displacement of the same towards the working end of the central conductor causes a radial spreading of the expansion sleeve, the drive element for clamping the change part in the central conductor so tensile forces must be transmitted, it is advantageous if the external thread the drive element for generating the axial displacement forces cooperates with a corresponding internal thread of an abutment element, which is supported axially on the expansion sleeve. This results in a simple construction with few components.

It is also preferred if the abutment element is designed as a hexagon nut or as a face nut with at least two end holes, which preferably have a circumferential, on its outer circumference, has radial bead, which can serve as field relief.

Advantageously, the drive element in this case between the spreader and the external thread on a preferably designed as a shank or as an expansion sleeve expansion region, advantageously with a length of at least twice, preferably at least four times the diameter of the external thread.

If, however, the expansion body is designed such that an axial displacement of the same in the direction away from the working end of the central conductor causes a radial spreading of the expansion sleeve, the drive element for clamping the change part in the central conductor must therefore transmit compressive forces, it is preferred if the external thread of the Drive element cooperates with a corresponding internal thread of an abutment member which is axially connected to the expansion sleeve for transmitting axial tensile forces between the abutment member and the expansion sleeve. If the abutment element is formed integrally with the expansion sleeve, which is preferred, the result is a conceivably compact construction with a minimum of components.

Advantageously, in this case, the expansion sleeve in the region between the abutment element and the region where it is spread radially from the spreader, an expansion region, which preferably has a length of at least twice, more preferably at least four times the diameter of the internal thread of the abutment member.

As has already been explained with reference to a few preferred embodiments mentioned above, the constructive provision of expansion areas for transmitting the forces required for the generation of contact forces between components of the exchangeable exchangeable part and the central conductor makes it possible to exchange forces between these components even under strong pressure pulsations in the working area, so that particularly robust and maintenance-free working electrodes can be provided over a long period of time.

Preferably, the drive element between electrode tip and spreader has a region with a non-rotationally symmetrical cross section, preferably at least two parallel mirror surfaces, which are positively connected with a tool such. a wrench can be taken, for the purpose of rotation of the drive member relative to the expansion sleeve and / or temporarily securing the same against rotation.

In yet another preferred embodiment of the working electrode, a seal, preferably an O-ring, is disposed between the changing part and the central conductor to prevent penetration of process liquid and dirt into the attachment area between the change part and the central conductor. In particular, in embodiments in which the removable part is connected via the aforementioned first screw to the central conductor, thereby a contamination and damage of the same can be prevented.

In yet another preferred embodiment of the working electrode, the central conductor in the region of its working end, where it emerges from the insulator body, on its outer circumference on a circumferential, radial bead.

In yet another preferred embodiment of the working electrode, the central conductor in the region of its Arbeitsendseitigen exit from the insulator body on a region with a non-rotationally symmetrical cross-section, preferably two parallel mirror surfaces, for positive cooperation with a tool such. a fork wrench.

Alternatively or additionally, it is preferred if the central conductor at its end of work End face has at least two end holes for positive engagement with a face spanner.

By these embodiments, it is possible to secure the central conductor during assembly and / or disassembly of the removable part against rotation in the insulator, which in force-locking, for example. central conductors secured by press-fitting or shrink-fitting in the insulator could lead to a disintegration or destruction of the connection with the insulator.

In preferred embodiments of the working electrode, the electrode tip is formed as a spherical cap or as a paraboloid of revolution. Such molds provide a locally defined breakdown starting point while maintaining good electrode tip life

A second aspect of the invention relates to a replacement part for a working electrode according to the first aspect of the invention. The change part has an expansion sleeve and a preferably cone-shaped or pyramid-shaped expansion body, which is arranged at least partially within the expansion sleeve and cooperates with it in such a way that the expansion sleeve by an axial displacement of the expansion body relative to it in a region, preferably an end portion of the expansion sleeve , can be spread radially. Here, the spreader, preferably cohesively, such as by integral training or by soldering or welding, connected to a drive element for moving the spreader in the expansion sleeve, which protrudes at its end remote from the spreader from the expansion sleeve and at this end a kugelkalottenförmige or rotationsparaboloidförmige Electrode tip forms. Between the electrode tip and the expansion body, the drive element has an external thread on which a preferably nut-like abutment element is arranged with a corresponding internal thread is. The abutment member is axially supported on the expansion sleeve, so that a rotation thereof relative to the drive element can cause an axial movement of the expansion element connected to the drive element in the direction of the electrode tip, which then leads to an increasing spreading of the expansion sleeve.

In a preferred embodiment of the change part, the abutment element is designed as a face nut, preferably with at least two, more preferably with at least four end holes distributed with the same pitch. In this case, it is further preferred if the face-end nut forms an encircling, radial bead on its outer circumference, and more preferably if it has substantially the shape of a disk with rounded peripheral edges. In this way, the abutment element can additionally serve as a field relief.

In a further preferred embodiment of the removable part, the drive element between the spreader and the external thread on a preferably designed as a stretch or expansion sleeve expansion region, preferably with a length of at least twice, more preferably at least four times the diameter of the external thread.

A third aspect of the invention relates to a replacement part for a working electrode according to the first aspect of the invention. The change part has an expansion sleeve and a particular conical or pyramidal expansion body for radially spreading the expansion sleeve by axial displacement of the same relative to the expansion sleeve. In this case, the expansion body is preferably cohesively, such as connected by one-piece design or by welding or soldering, with a drive element for moving the expansion body in the expansion sleeve. The drive element protrudes at its end facing away from the spreader out of the expansion sleeve and is at this end as kugelkalottenförmige or one formed Rotationsparaboloidförmige electrode tip. Between the electrode tip and the expansion body, the drive element also has an external thread which cooperates with a corresponding internal thread of an abutment element. The abutment element is, preferably by integral formation, connected to the expansion sleeve, so that a transmission of axial tensile forces between the abutment element and the expansion sleeve is possible and caused by rotation of the drive element relative to the abutment element axial movement of the spreader in a direction away from the electrode tip can be, which then leads to an increasing spreading of the expansion sleeve.

In a preferred embodiment of the interchangeable part, the expansion sleeve in the region between the abutment member and the region where it is spread radially from the spreader, an expansion region, preferably with a length of at least twice, more preferably at least four times the diameter of the internal thread of the abutment member , Typically, such strain ranges can be recognized by the fact that they have a reduced cross-section in order to obtain a rigid stiffness characteristic as little as possible.

The change parts according to the second and third aspects of the invention are preferred commercial goods and allow the construction of working electrodes, in which the electrode tip can be changed easily without disconnecting the electrode from the voltage supply system.

A fourth aspect of the invention relates to the use of the working electrode according to the first aspect of the invention for the electrodynamic fragmentation of preferably poorly conductive materials such as concrete or slag. In such uses, the benefits of the invention are particularly evident.

BRIEF DESCRIPTION OF THE DRAWINGS

• Fig. 1 einen Längsschnitt durch das Arbeitsende einer ersten erfindungsgemässen Arbeitselektrode;
• Fig. 2 einen Längsschnitt durch das Arbeitsende einer zweiten erfindungsgemässen Arbeitselektrode; und
• Fig. 3 einen Längsschnitt durch das Arbeitsende einer dritten erfindungsgemässen Arbeitselektrode.

Further embodiments, advantages and applications of the invention will become apparent from the dependent claims and from the following description with reference to FIGS. Showing:

• Fig. 1 a longitudinal section through the working end of a first inventive working electrode;
• Fig. 2 a longitudinal section through the working end of a second inventive working electrode; and
• Fig. 3 a longitudinal section through the working end of a third inventive working electrode.

WAYS FOR CARRYING OUT THE INVENTION

Fig. 1 shows the working end of a first inventive working electrode in longitudinal section. As can be seen, the electrode comprises a cylindrical and towards the working end stepwise frusto-conically tapering insulator body 1 made of plastic, with a central conductor 2 arranged in its center made of stainless steel, which is shrunk into the insulator body 1. The central conductor 2 has at its end face on the working side a central cylindrical blind hole which opens towards the working end, at which the central conductor 2 emerges from the insulator body 1 with the formation of a circumferential radial bead 14. Arranged in the central bore of the central conductor 2 is a claim according to exchange part 4, comprising a cylindrical, slotted at one end expansion sleeve 24 (not shown cut), which is spread radially by means of a frusto-conical expansion body 25 at its slotted end, such that they in Area of this end is pressed radially to the wall 26 of the blind hole bore and thereby clamped axially immovable in the blind hole. The expansion body 25 is integral with a drive member 27 for axially displacing the same in the expansion sleeve for the purpose of effecting the radial spreading the expansion sleeve is formed, which protrudes at its end remote from the spreader 25 from the expansion sleeve 24 and terminates at this end in a spherical cap electrode tip 3. Between the electrode tip 3 and the spreader 25, the drive element 27 has an external thread 28 on which an abutment element 29 designed as a hexagon nut (not shown cut) is arranged with a corresponding internal thread. The abutment member 29 is axially supported on the expansion sleeve 24 (not on the inner conductor 2), so that a rotation of the same relative to the drive member 27 can cause axial movement of the drive member 27 connected to the expansion body 25 in the direction of the electrode tip 3, which Then leads to an increasing spreading of the expansion sleeve 24 and to increase the clamping forces between the wall 26 of the blind hole and the expansion sleeve 24. In order to obtain as "soft" a spring characteristic as possible for the provision of the axial forces of the drive element 27 which ultimately bring about the clamping forces, the drive element 27 is designed as a stretch shaft in the area between the expansion body 25 and the external thread 28 (not visible in the figure). In order to relieve the expansion of the drive member 27 when tightening the nut 29 for spreading and clamping of the expansion sleeve 24 or when loosening the nut 29 in order to remove the removable part 4 of damaging torsional forces, the drive element 27 in the region between the electrode tip 3 and the external thread 28th four each on 90 ° circumferentially offset mirror surfaces 12 at which a fork wrench can be attached to secure the drive member 27 against rotation when tightening or loosening the nut 29th

Fig. 2 shows the working end of a second inventive working electrode in longitudinal section, which essentially corresponds in construction to the above-described working electrode. Unlike the in Fig. 1 embodiment shown, however, the inner conductor 2 is formed in the present case as a pure cylinder sleeve without radial bead and the abutment member 29 as a disk-shaped Stirnlochmutter with four end holes 23 and rounded peripheral edges, which here form the radial bead 14 of the field relief. It is also noticeable that the expansion sleeve 24 in this embodiment is shorter and significantly larger in circumference, the expansion body 25 is rather plate-shaped and visible here the expansion shaft 8 of the drive member 27 is shorter than in the example in Fig. 1 , The insulator body 1, the electrode tip 3, the mirror surfaces 12 and the external thread 28 of the drive element 27 are, however, identical.

Fig. 3 shows the working end of a third inventive working electrode in longitudinal section. As can be seen, the electrode here also comprises a cylindrical insulator body 1 which is of frusto-conical shape towards the working end and in the center of which a central conductor 2 is arranged. The central conductor 2 has at its end face on the working end side a central cylindrical bore which, towards the working end, on which the central conductor 2 emerges from the insulator body 1 with the formation of a circumferential radial bead 14, is opened. The radial bead 14 is provided with end bores 23 for engaging a face hole key. Arranged in the central bore of the central conductor 2 is an inventive change part 4, which in the present case comprises an expansion sleeve 24 and a conical spreader 25 for radially spreading the expansion sleeve 24 by axial displacement relative to the same. The expansion body 25 is integrally connected to a drive element 27 for displacing the expansion body 25 in the expansion sleeve 24, which protrudes at its end facing away from the expansion body of the expansion sleeve 24 and is formed at this end as a spherical cap electrode tip 3. Between the electrode tip 3 and the spreader 25, the drive element 27 also has an external thread 28 which is screwed into a corresponding internal thread at the working end of the expansion sleeve 24. This area of the expansion sleeve 24 forms a claimed abutment element. Spreader body 25, drive member 27, external thread 28 and electrode tip 3 are thus formed here of a one-piece Einschraubteil, which also has mirror surfaces 12 for cooperation with an insertion or Ausschraubwerkzeug and when screwing into the expansion sleeve 24 automatically a spread and corresponding clamping of the same in the bore in the central conductor 2 causes. So that no torsional forces are introduced into the contact surface between the central conductor 2 and the insulator body 1, the central conductor 2 is expediently secured against twisting when screwing in or unscrewing this screw-in part with a face-hole key. As can further be seen, the expansion sleeve 24 in the region between the internal thread, which cooperates with the external thread 28 of the drive element 27, and the region where it is radially spread by the expansion body 25, a significantly reduced in cross-section area 9, which represents an expansion sleeve 9 with a length of about four times the diameter of the internal thread.

While preferred embodiments of the invention are described in the present application, it should be clearly understood that the invention is not limited to these and may be practiced otherwise within the scope of the following claims.

Claims (21)

Working electrode for an electrodynamic fragmentation system, comprising an insulator body (1) with a central conductor (2), at the working end of which an electrode tip (3) is arranged, which is formed by an exchangeable exchangeable part (4), wherein the exchangeable part (4) passes by a force fit Clamping in a frontal opening in the working end of the central conductor (2) is fixed, characterized in that the interchangeable part comprises an expansion sleeve (24) with an expansion body (25) for radially spreading the expansion sleeve (24), by means of which they radially to the wall (26) of the frontal opening is pressed or pressed to effect the clamping. Working electrode according to claim 1, wherein the expansion body (25) has a particular conical or pyramidal portion for radially spreading the expansion sleeve (24) and wherein the expansion body (25), in particular by one-piece design, with a drive element (27) for axial displacement of the Spreader (25) for the purpose of spreading the expansion sleeve (24) is connected, which emerges at the working end of the central conductor (2) from the frontal opening and at its end facing away from the spreader (25) an electrode tip (3). Working electrode according to claim 2, wherein the drive element (27) between the electrode tip (3) and the expansion body (25) has an external thread (28) for generating an axial displacement force. Working electrode according to claim 3, wherein the expansion body (25) is designed such that an axial displacement thereof towards the working end of the central conductor (2) towards a radial spreading of the expansion sleeve (24) causes and wherein the external thread (28) of the drive element ( 27) with a corresponding internal thread of a nut-like abutment element (29) cooperates, which is supported axially on the expansion sleeve (24). Working electrode according to claim 4, wherein the nut-like abutment element (29) is formed as a face nut with at least two end holes (23), which forms in particular on its outer circumference a circumferential, radial bead (14). Working electrode according to one of claims 4 to 5, wherein the drive element (27) between the spreader (25) and the external thread (28) has an expansion region, in particular with a length of at least twice the elongation shaft (8) or expansion sleeve Diameter of the external thread (28). A working electrode according to claim 2, wherein the expansion body (25) is formed such that an axial displacement thereof in the direction away from the working end of the central conductor (2) causes a radial spreading of the expansion sleeve (24) and wherein the external thread (28) of the drive element ( 27) cooperates with a corresponding internal thread of an abutment element (29) which is connected to the expansion sleeve (24) for transmitting axial tensile forces between the abutment element (29) and the expansion sleeve (24) and in particular, which integral with the expansion sleeve (24). is trained. Working electrode according to claim 7, wherein the expansion sleeve (24) in the region between the abutment element (29) and the area where it is radially spread by the expansion body (25), a strain region (9) in particular with a length of at least twice the diameter of the Innengwindes the abutment member (29). Working electrode according to one of the preceding claims, wherein the drive element (27) between the electrode tip (3) and expansion body (25) has a region with a non-rotationally symmetrical cross section, in particular, two parallel mirror surfaces (12), for positive engagement with a tool for rotating or Verdrehsichern same. Working electrode according to one of the preceding claims, wherein between the change part (4) and the central conductor (2) a seal (13), in particular an O-ring (13) is arranged to prevent penetration of process fluid into an area formed between them , which serves to fasten the replacement part (4) to the central conductor (2). Working electrode according to one of the preceding claims, wherein the central conductor (2) in the region of its working-side outlet from the insulator body (1) has on its outer circumference a circumferential, radial bead (14). Working electrode according to one of the preceding claims, wherein the central conductor (2) in the region of its Arbeitsendseitigen outlet from the insulator body (1) has a region with a non-rotationally symmetrical cross section, in particular two parallel mirror surfaces (12), for positive cooperation with a wrench. Working electrode according to one of the preceding claims, wherein the central conductor (2) has at least two end holes (23) on its end face on the working end, for positive engagement with a face spanner. Working electrode according to one of the preceding claims, wherein the electrode tip (3) has the shape of a spherical cap or a paraboloid of revolution. Exchange part (4) for a working electrode according to one of the preceding claims, comprising an expansion sleeve (24) and a particular conical or pyramidal expansion body (25) for radial spreading of the expansion sleeve (24) by axial displacement thereof relative to the expansion sleeve (24) the spreader (25) in particular cohesively with a drive element (27) for moving the expansion body (25) in the expansion sleeve (24) is connected, which at its end facing away from the spreader (25) from the expansion sleeve (24) and exits at this end a kugelkalottenförmige or rotationsparaboloidförmige Electrode tip (3) and wherein the drive element (27) between the electrode tip (3) and the spreader (25) has an external thread (28) and arranged on the external thread (28) has a particular nut-like abutment member (29) which axially the expansion sleeve (24) is supported, so that by rotation of the same relative to the drive element (27) an axial movement of the spreader (25) in the direction of the electrode tip (3) is effected, with increasing spreading of the expansion sleeve (24). Interchangeable part (4) according to claim 15, wherein the abutment element (29) as a face nut, in particular with at least two end holes (23) is formed, which forms a circumferential, radial bead (14) in particular on its outer periphery. Interchangeable part (4) according to one of claims 15 to 16, wherein the drive element (27) between the spreader (25) and the external thread (28) has an expansion region, in particular designed as a stretch shank (8) or as an expansion sleeve, in particular with a length of at least twice the diameter of the external thread (28). Exchange part (4) for a working electrode according to one of claims 7 to 8, comprising an expansion sleeve (24) and a particular conical or pyramidal expansion body (25) for radial spreading of the expansion sleeve (24) by axial displacement thereof relative to the expansion sleeve (24) , wherein the expansion body (25) in particular cohesively with a drive element (27) for displacing the expansion body (25) in the expansion sleeve (24) is connected, which at its the Spreizkörper (25) facing away from the expander sleeve (24) and at this end forms a kugelkalottenförmige or rotationsparaboloidförmige electrode tip (3) and wherein the drive element (27) between the electrode tip (3) and the spreader (25) has an external thread (28 ), which cooperates with a corresponding internal thread of an abutment element (29), which is connected to the expansion sleeve (24) for transmitting axial tensile forces between the abutment element (29) and the expansion sleeve (24), so that by rotation of the drive element (27 ) relative to the abutment element (29) an axial movement of the spreader (25) in a direction away from the electrode tip (3) is effected, with increasing spreading of the expansion sleeve (24). Exchange part (4) according to claim 18, wherein the abutment element (29) is formed integrally with the expansion sleeve (24). Interchangeable part (4) according to any one of claims 18 to 19, wherein the expansion sleeve (24) in the region between the abutment element (29) and the region where it is radially spread by the expansion body (25), an expansion region (9), in particular with a Length of at least twice the diameter of the Innengwindes of the abutment member (29). Use of the working electrode according to one of claims 1 to 14 for the electrodynamic fragmentation of, in particular, poorly conductive material, in particular concrete or slag.

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