COOLED ELECTRODE FOR PLASMA TORCH

Description

[0001] The present invention relates to the field of the electrodes for plasma cutting and in particular it refers to a fluid-cooled electrode for plasma torch, which particularly is air-cooled or gas-cooled.

[0002] Electrodes for plasma cutting are known, which are contained in a calibrated nozzle of a plasma torch, between the nozzle and the electrode there is an interspace which allows the passage of a gas, which permits, by means of the start of an arc, to generate the plasma and thus to proceed to the cut of metal sheets, remarkable thickness sheets included.

[0003] Usually such electrodes have a life which is normally considered to be short before the electrode is unusable for further cuts because of the wear, which is consequent on the very high reached temperatures.

[0004] Thus electrodes cooling systems are used for example by means of auxiliary channels, which are inside the electrodes which carry a fluid apt to the cooling of said electrodes. Such channels has the disadvantage of being bulky, difficult to realise, and expensive above all in plasma torches for manual use, and thus the simpler torches are favourite without cooling system inside the electrode.

[0005] An object of the present invention is to propose an electrode with better cooling capacities and with a reduced wear and which is simple even if without internal cooling ducts.

[0006] Another object of the present invention is to propose an electrode which allows a better operative cooling and a longer duration of the cut.

[0007] Documents US5208441 A and US 2015/351214 A1 disclose an electrode provided with the features of the preamble of claim 1 of the present document. US 2011/108528 A1 discloses a nozzle provided with fins. The characteristics of the invention are underlined below with particular reference to the enclosed drawings in which:

• figures 1 and 2 show respective perspective and frontal views of the electrode object of the present disclosure;
• figures 3 and 4 show respective perspective and frontal views of a first variant of the electrode of figure 1;
• figures 5 and 6 show frontal views of respective variant second and third of the electrode of figure 1.

[0008] With reference to figures 1 and 2, numeral 1 indicates the electrode object of the present disclosure comprising a body 3 which has a fixing end 5 for its connection to a torch and a free end 7.

[0009] The body 3 shown in figures 1 and 2 is equipped with two annular fins 11 which stick out from the portion of the body 3, said portion being located between the fixing ends 5 and free end 7.

[0010] The body 3 can have from two to six fins 11 which are parallel and spaced, preferably said body 3 is equipped with three fins 11.

[0011] Said fins 11 are assigned to improve the cooling of the electrode 1 by the gas flow, which passes between the electrode and the nozzle, said gas flow licking said fins.

[0012] The fins 11 have an outer diameter ranging from 130% to 180% of the diameter of the body of the electrode 1.

[0013] In the event that a current variable from 100 A (Ampere) to 150 A is used it is better that the fins 11 have a diameter of almost 180% of the dimension of the electrode 1.

[0014] In the event that a current ranging from 20 A to 50 A is used it is better that the fins 11 have a diameter of almost 130% of the dimension of the electrode.

[0015] The fins 11 have a tapered profile fit to improve the heat dissipation and thus to increase the heat transfer between the electrode 1 and the gas.

[0016] In the preferred embodiment of the electrode 1, each fin 11 has a flat annular face nearly perpendicular to the longitudinal geometric axis of the electrode 1 and an opposed truncated cone shaped face whose geometrical axis coincides with the axis of the electrode 1. The truncated cone shaped face of the fin 11 is downstream of the flat face compared to the direction of the gas flow.

[0017] A first variant of the electrode 1 shown in figures 3 and 4 has three fins 11.

[0018] A second variant of the electrode 1, shown in figure 5, provides that the truncated cone shaped face of each fin 11 is upstream of the flat face compared to the direction of the gas flow.

[0019] In figure 6 a third variant of the electrode 1 is shown, in which each fin 11 has two truncated cone shaped annular faces whose geometric axis coincides with the longitudinal geometric axis of the electrode 1.

[0020] In the preferred embodiment and in the three variants of electrode 1, the free external edges of the two faces of each fin 11 are connected by a bevelled or curved edge. Moreover, at least one face of each fin 11 has a curved profile connected to the electrode 1.

[0021] The fins 11 are made integral to the electrode 1 of copper or of other appropriate material.

[0022] The bigger heat dissipation and the consequent prolongation of the life of the electrode 1 is estimable with an augmentation of 40% - 50% in using electrode 1 with elevated currents (100 - 150 A) up to an augmentation of 70% employing lower currents (20 - 50 A). This evaluation emerges from measurements carried out during standard tests throughout cuts in automation.

[0023] These tests provide "work cycles" each one composed by a cut carried out on an iron plate starting from the solid, such cut lasts 20 seconds with a stop of 4 seconds between a cut and the next one. For example the cut of a plate of 12,7 mm requires a 100 A cutting current.

[0024] An advantage of the present invention is to provide an electrode with better cooling capacities and with a reduced wear independently from the presence or otherwise of internal cooling ducts.

[0025] Another advantage of the present invention is to provide an electrode which allows a better operative cooling and a longer duration of the cut.

Claims

1. Cooled electrode for plasma torch comprising a body (3) having a fixing end (5) for connecting to torch and a free end (7); said body (3) is provided with at least two annular fins (11) projecting from the body (3) between said fixing end (5) and free end (7), being said two fins intended to improve the cooling of electrode (1) by a gas licking thereto; the fins (11) have a tapered profile fit to improve heat dissipation at said electrode (1); said electrode (1) being characterized in that each fin (11) has two truncated cone annular faces with geometric axis corresponding with the longitudinal geometric axis of the electrode (1).

2. Electrode according to claim 1 characterized in that the body (3) has two to six parallel and spaced fins (11).

3. Electrode according to claims 1 or 2 characterized in that said fins (11) have an outer diameter ranging from 130% to 180% of body (3) diameter of electrode (1).

4. Electrode according to any of preceding claims characterized in that the free edges of the two faces of each fin (11) are connected by a beveled or curved edge.

5. Electrode according to any of preceding claims characterized in that at least one face of each fin (11) has a curved profile connected to the body (3) of the electrode (1).

Ansprüche

1. Gekühlte Elektrode für einen Plasmabrenner, umfassend einen Körper (3) mit einem Befestigungsende (5) zum Verbinden mit dem Brenner und mit einem freien Ende (7), wobei der Körper (3) mit mindestens zwei ringförmigen Rippen (11) ausgestattet ist, die vom Körper (3) zwischen dem Befestigungsende (5) und dem freien Ende (7) abstehen, wobei beide Rippen dazu vorgesehen sind, das Abkühlen der Elektrode (1) durch ein darauf strömendes Gas zu verbessern,
wobei die Rippen (11) ein sich verjüngendes Profil aufweisen, um die Wärmeabgabe an der Elektrode (1) zu verbessern,
und die Elektrode ist dadurch gekennzeichnet, dass jede Rippe (11) zwei konische Ringflächen mit einer geometrischen Achse aufweist, die der geometrischen Längsachse der Elektrode (1) entspricht.

2. Die Elektrode gemäß Anspruch 1, dadurch gekennzeichnet, dass der Körper (3) zwei bis sechs parallel verlaufende und voneinander beabstandete Rippen (11) aufweist.

3. Die Elektrode gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Rippen (11) einen äußeren Durchmesser aufweisen, der 130 % bis 180 % des Durchmessers des Körpers (3) der Elektrode (1) ausmacht.

4. Die Elektrode gemäß einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die freien Kanten der beiden Fläche jeder Rippe (11) über eine abgeschrägte oder gekrümmte Kante verbunden sind.

5. Die Elektrode gemäß einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass mindestens eine Fläche jeder Rippe (11) ein gekrümmtes Profil aufweist, das mit dem Körper (3) der Elektrode (1) verbunden ist.

Revendications

1. Électrode refroidie pour torche à plasma comprenant un corps (3) ayant une extrémité de fixation (5) pour une liaison à une torche et une extrémité libre (7) ; ledit corps (3) comporte au moins deux ailettes annulaires (11) se projetant à partir du corps (3) entre ladite extrémité de fixation (5) et ladite extrémité libre (7), lesdites deux ailettes étant destinées à améliorer le refroidissement de l'électrode (1) par un gaz humectant celle-ci ; les ailettes (11) ont un profil effilé adapté pour améliorer une dissipation de chaleur au niveau de ladite électrode (1) ; ladite électrode (1) étant caractérisée par le fait que chaque ailette (11) a deux faces annulaires tronconiques avec un axe géométrique correspondant à l'axe géométrique longitudinal de l'électrode (1).

2. Électrode selon la revendication 1, caractérisée par le fait que le corps (3) a de deux à six ailettes parallèles et espacées (11).

3. Électrode selon la revendication 1 ou 2, caractérisée par le fait que lesdites ailettes (11) ont un diamètre externe dans la plage allant de 130 % à 180 % du diamètre du corps (3) de l'électrode (1).

4. Électrode selon l'une quelconque des revendications précédentes, caractérisée par le fait que les bords libres des deux faces de chaque ailette (11) sont reliés par un bord biseauté ou incurvé.

5. Électrode selon l'une quelconque des revendications précédentes, caractérisée par le fait qu'au moins une face de chaque ailette (11) a un profil incurvé relié au corps (3) de l'électrode (1).

Drawing