High-power pulsed electric discharge firing tool
By incorporating a tip of high-melting-point materials like rhenium or tungsten on the electrodes, the wear issue is mitigated, enhancing the durability and shot count of high-power pulsed electrical discharge tools.
Patent Information
- Application Number
- FR2023000234
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-01-10
- Publication Date
- 2025-12-26
- Estimated Expiration
- 2043-01-10
AI Technical Summary
Existing high-power pulsed electrical discharge tools experience rapid wear of electrodes, leading to frequent replacements that are costly in terms of time and money due to the use of large, one-piece electrodes made of resistant materials like steel or copper-tungsten alloys.
The electrodes are composed of a body made of a first material, such as steel, with a tip made of a second material like rhenium, molybdenum, or tungsten, which is securely fixed to the firing end, allowing for increased durability and reduced wear.
The solution enables the electrodes to withstand several thousand shots, significantly extending their lifespan compared to conventional designs, reducing maintenance costs and downtime.
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Abstract
Description
Title of the invention: High-power pulsed electric discharge firing tool technical field
[0001] The present invention relates to the field of high-power electrical discharge tools and more particularly to a pulsed high-power electrical discharge tool. Previous technique
[0002] In the field of high-power pulsed tools, it is known to use a pair of electrodes between which a high voltage is applied in order to induce an electrical discharge. Such high voltages can be on the order of 10 to 300 kV.
[0003] Such tools are used for example to crush rock on the surface to reduce it into small pieces.
[0004] In order to withstand high discharge voltages and powers, the electrodes used are large and made of resistant materials such as, for example, steel or copper-tungsten alloys. Existing electrodes are in the form of an elongated, one-piece body having a cylindrical mounting end and a substantially rounded firing end.
[0005] However, wear appears on the tip of the electrodes which can render them unusable after a few hundred shots.
[0006] However, each change of electrodes requires stopping the tool and can therefore prove costly in both time and money.
[0007] It would therefore be advantageous to propose a solution that would at least partially remedy these drawbacks. Description of the invention
[0008] One of the aims of the invention is to provide a simple and efficient high-power pulsed tool solution. Another aim of the invention is to provide a high-power pulsed tool solution comprising reliable and durable electrodes.
[0009] To this end, the invention first relates to a high-power pulsed electrical discharge tool, said tool comprising a plurality of electrodes mounted on an electrode holder, each of the electrodes comprising an elongated body, fixed on said electrode holder, and a firing end, configured to allow the start or arrival of an electric arc, each electrode being notable in that, the body being made of a first material, it comprises a tip made of a second material, different from the first material, mounted at the firing end of the body.
[0010] The use of a tip significantly slows down wear on the end of body firing, thus allowing for more shots to be taken.
[0011] In one embodiment, the tip is in the form of an insert housed coaxially with the body in a receiving cavity formed in the firing end, preferably so as to be flush with the firing end of the body. Such an insert is securely fixed to the firing end of the body, which allows the electrode to wear slowly.
[0012] In one embodiment, the nozzle is in the form of a solid cylinder mounted coaxially on the firing end of the body, protruding from said firing end by a predetermined distance.
[0013] Preferably, the first material is a metal or a metal alloy suitable for resisting the mechanical stresses generated by the electric arc.
[0014] Preferably, the second material is a metal or a metal alloy suitable for resisting the mechanical stresses generated by the electric arc.
[0015] Advantageously, the second material has a melting point above 2500 °C in order to reduce erosion.
[0016] Advantageously still, the second material is chosen from rhenium and / or molybdenum and / or tungsten in order to reduce erosion.
[0017] According to one aspect of the invention, the first material is ductile, which allows it to withstand shocks generated by electrical discharges.
[0018] According to another aspect of the invention, the first material is a metal.
[0019] Preferably, the first material is steel.
[0020] Advantageously, the body is one piece.
[0021] Advantageously still, the firing end of the body is substantially rounded.
[0022] In one embodiment, the body's fixing end has a cylindrical shape.
[0023] The invention also relates to a method for manufacturing a tool as described above, said tool comprising an electrode holder, said method comprising, for each electrode, the steps of:
[0024] - manufacturing of the body, for example by molding or machining,
[0025] - manufacturing of the tip, for example also by molding or machining,
[0026] - assembly of the body and the tip, preferably by press fitting the tip on the firing end of the body,
[0027] then a step of fixing the two assembled electrodes onto the electrode holder. Brief description of the drawings
[0028] Other features and advantages of the invention will become apparent from the following description. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:
[0029] [Fig.1] Fig.1 schematically illustrates one embodiment of a tool according to the invention.
[0030] [Fig.2] Fig.2 schematically illustrates a first embodiment of an electrode for the tool according to the invention in longitudinal section view.
[0031] [Fig.3] Fig.3 schematically illustrates a second embodiment of an electrode for the tool according to the invention in longitudinal section view.
[0032] [Fig.4] Fig.4 schematically illustrates a method of manufacturing the tool according to the invention. Description of the implementation methods
[0033] Figure 1 shows an example of a pulsed high-power electrical discharge tool according to the invention. The tool can, for example, be a tool for electro-hydraulic forming (EHF) or a crushing cell by direct or indirect electro-hydraulic effect (in the direct effect, the rock is positioned between the electrodes and the electrical discharge passes through the rock; in the indirect effect, the rock is not located between the electrodes, the electrical discharge occurs in the water, generating a shock wave that will impact the rock).
[0034] The tool 1 includes an electrode holder 10 and electrodes 20, mounted on said electrode holder 10.
[0035] Tool 1 includes electrical means (not shown) configured to apply a high voltage, preferably for example between 10 and 300 kV, between the electrodes 20 in order to trigger an electrical discharge between said electrodes 20.
[0036] In such a tool 1, the electrodes 20 operate in pairs (anode-cathode), as in the example of [Fig.1], or more (for example one anode and several cathodes).
[0037] The medium between the electrodes 20, intended to receive the shot(s), is a solid and / or gaseous medium. The tool 1 can, for example, be used to fracture or crush rock by delivering an electrical discharge generated by the application of high voltage between the electrodes 20. Such a tool 1 makes it possible, for example, to perform several thousand shots.
[0038] Figures 2 and 3 illustrate two embodiments of an electrode 20 for tool 1 according to the invention.
[0039] Each electrode 20 comprises a body 210 and a tip 220.
[0040] The body 210 has an elongated shape extending along a longitudinal axis X.
[0041] In both of these examples, the body 210 is monobloc.
[0042] The body 210 is made of a first material which is ductile, that is to say, which can be elongated, extended, stretched without breaking. The first material can be a metal or a metal alloy, for example steel.
[0043] The body 210 includes a fixing end 21 OA and a firing end 210B.
[0044] The 210A attachment end is configured to allow the electrode to be attached on an electrode holder 10 of tool 1.
[0045] The firing end 210B is configured to allow the output of electrical energy to another electrode in order to form an arc synonymous with electrical discharge or the input of electrical energy from an arc extending from another electrode.
[0046] To this end, in the examples of figures 2 and 3, the firing end 210B has a substantially rounded shape on the circular periphery of its free part.
[0047] The firing end 210B is configured to receive the tip 220.
[0048] The tip 220 is fixed at the firing end 210B of the body 210.
[0049] The 220 nozzle is made of a second material, different from the first material.
[0050] The second material is a metal or a metal alloy or a shrink-fitted alloy. Preferably, the second material is chosen from rhenium, molybdenum, tungsten or an alloy of at least two of these three metals.
[0051] The second material is ductile and has a melting point above 2500 °C.
[0052] Example from [Fig. 2]
[0053] In this second example, the tip 220 is in the form of a solid cylindrical insert, with a rectangular longitudinal cross-section, housed coaxially to the longitudinal axis X of the body 210 in a central receiving cavity 210B1, extending over a length L, also coaxially to the longitudinal axis X of the body 210, formed in the firing end 210B and flush with the distal portion 210BD of the firing end 210B of the body 210. Preferably, the tip 220 has a length greater than 1 cm in order to improve its attachment to the body 210 and thus the resistance of the electrode 1.
[0054] Example of [Fig.3]
[0055] In this third example, the tip 220 is in the form of a solid cylindrical insert with a rectangular longitudinal cross-section, housed coaxially with the longitudinal axis X of the body 210 in a central receiving cavity 210B1, extending over a length L, also coaxially with the longitudinal axis X of the body 210, formed in the firing end 210B. The tip 220 extends from the firing end 210B by a distance D. The distance D can, for example, be between 1 and 30 mm. The tip 220 thus has a length (L+D).
[0056] The example in [Fig.2] allows for solidity and effective retention of the insert, while the example in [Fig.3] allows for increasing the electric field at the end of the insert and thus reducing the time to create the discharge, thereby improving the efficiency of the intended application, for example, rock crushing.
[0057] Manufacturing example
[0058] The tool manufacturing process 1 according to the invention first includes the manufacturing of the electrode holder 10 in a step E0.
[0059] Next, the body 210 of each electrode 20 is manufactured in a step El, for example by molding or machining, during which the receiving cavity 210B1 is formed in the firing end 210B of the body 210.
[0060] In parallel, the process includes, again for each electrode 20, the manufacture of the tip 220, for example also by molding or machining, in a step E2.
[0061] The method then includes, again for each electrode 20, the assembly of the body 210 and the tip 220 in a step E3. More specifically, the tip 220 is fixed to the firing end 210B of the body 210. This fixing can, for example, be a press fit so that the tip 220 is securely fixed by friction to the firing end 210B of the body 210.
[0062] Finally, the electrodes 20 are fixed onto the electrode holder 10 in a step E4.
[0063] Tests
[0064] Tests carried out on the different types of electrodes show that the electrodes in the examples in Figures 2 and 3 can withstand several thousand shots (at least 5000 shots on average according to the tests) in a durable manner, in particular showing low wear at the end of the tests compared to existing conventional solutions.
[0065] The 220 tip therefore makes it possible to significantly increase the resistance of the 20 high power electrodes.
Claims
Demands
1. High-power pulsed electrical discharge tool (1), said tool (1) comprising a plurality of electrodes (20) mounted on an electrode holder (10), each of the electrodes (20) comprising an elongated body (210), fixed on said electrode holder (10), and a firing end (210B), configured to permit the start or arrival of an electric arc, each electrode (20) being characterized in that, the body (210) being made of a first metal material or a metal alloy, it comprises a tip (220) made of a second material being a metal or a metal alloy different from the first material, said tip (20) being in the form of a solid cylindrical insert housed coaxially with the body (210) in a receiving cavity (210B1) formed in the firing end (210B).
2. Tool (1) according to claim 1, wherein the insert is housed in the receiving cavity (21 OBI) so as to come flush with the firing end (210B) of the body (10).
3. Tool (1) according to claim 1, wherein the tip (220) is in the form of a solid cylinder mounted coaxially on the firing end (210B) of the body (210) protruding from said firing end (210B) by a predetermined distance (D).
4. Tool (1) according to the preceding claim, wherein the second material has a melting point greater than 2500 °C.
5. Tool (1) according to any one of the preceding claims, wherein the second material is selected from rhenium and / or molybdenum and / or tungsten.
6. Tool (1) according to any one of the preceding claims, wherein the first material is ductile.
7. Tool (1) according to any one of the preceding claims, wherein the first material is steel.
8. A method for manufacturing a tool according to any one of the preceding claims, said tool comprising an electrode holder, said method comprising, for each electrode, the steps of manufacturing the body, manufacturing the tip and assembling the body and the tip, and then a step of fixing the two assembled electrodes onto the electrode holder.