EP1363479A2

EP1363479A2 - Plasma cutting torch device with interchangeable elements for pneumatic and electric arc striking

Info

Publication number: EP1363479A2
Application number: EP03010685A
Authority: EP
Inventors: Massimo Santini
Original assignee: Tecmo SRL
Current assignee: Tecmo SRL
Priority date: 2002-05-14
Filing date: 2003-05-13
Publication date: 2003-11-19
Also published as: ITBO20020298A1; ITBO20020298A0

Abstract

A plasma cutting torch device with interchangeable elements for pneumatic and electric arc striking is provided with a body (2) having a mobile element (7) sliding into a tubular element (8) to which a nozzle (9) for the plasma jet exit is removably fixed.

The device includes:

first interchangeable electrode (4) and bush (3) members and second interchangeable electrode (6) and bush (5) members;
a connection means (10) carried out in a end portion of the mobile element (7);

In a pneumatic striking working condition (P) of the device (1), the first interchangeable bush member (3) is removably locked between the tubular element (8) and the nozzle (9) and the first interchangeable electrode member (4) is fixed to the connection means (10) and is slidably moved by the mobile element (7) in the first interchangeable bush member (3), between a condition of contact (C) to the nozzle (9) and a condition of maximum distance (D) from the nozzle (9).

In an electric striking working condition (E), the second interchangeable bush member (5) and the second interchangeable electrode member (6), fixed to the connection means (10), are rigidly and removably locked to the tubular element (8) so fixing the mobile element (7) in the respective condition of maximum distance (DD) from the nozzle (9).

Description

The present invention relates to devices for cutting metallic elements and particularly refers to a plasma cutting torch device with interchangeable elements for pneumatic and electric arc striking.
There are known apparatuses for plasma cutting provided with manual torches in which the plasma jet is stricken by means of an initial striking power supply, having predefined frequency and voltage, applied to two coaxial electrodes.
There are also known plasma cutting apparatuses provided with torches in which the plasma jet striking is obtained by mutually and progressively moving apart the two coaxial electrodes, of which the inner one is pneumatically moved in order to strike an electric arc.
The main drawback of known torches consists in that they can work only with particular apparatuses capable to activate the respective striking devices.
An object of the present invention is to propose a plasma cutting torch device with pneumatic and electric arc striking capable to operate with apparatuses having electric and pneumatic arc striking by simply substituting some modular elements.
Further object is to propose a torch also provided with support means for supporting the element to be cut and provided with an efficient cooling system whose fluid flow does not perturb the plasma jet.
The above-mentioned objects are achieved according to the claim content.
The characteristics of the present invention are underlined in the following, with particular reference to the attached drawings, in which:

figure 1 shows a schematic longitudinal section view of a body of the device of the present invention;
figures 2 to 5 show longitudinal section views of respective interchangeable members of the device of the present invention;
figures 6 and 7 show enlarged longitudinal section views of the figure 1 body, associated with the interchangeable members of figures 2 and 3, in respective working conditions;
figure 8 shows an enlarged longitudinal section view of the figure 1 body associated with the interchangeable members of figures 4 and 5;
figure 9 shows an enlarged longitudinal section view of a variant of the figure 1 body associated with the interchangeable members of figures 2 and 3 in a condition;
figure 10 shows a longitudinal section view of a variant of the interchangeable member of figure 4;
figures 11 and 12 show reduced scale longitudinal section views of a variant of the figure 6 device in respective working conditions;
figure 13 shows a longitudinal section view of an element of figure 11;
figure 14 shows a reduced scale longitudinal section view of a further variant of the figure 6 device;
figures 15 and 16 show side views of an element of figure 14 respectively partially sectioned and axially rotated of 90°.

With reference to figures 1 to 8, numeral 1 indicates the device of the present invention including a body 2, first interchangeable bush members 3, first interchangeable electrode members 4, second interchangeable bush members 5 and second interchangeable electrode members 6. The interchangeable bush members 3,5 are usually also indicated with the term "diffuser".
The interchangeable members, first 3, 4 and second 5, 6, are alternatively fixed to the body 2 to allow striking conditions, respectively pneumatic striking condition P and electric striking condition E, of the plasma jet.
The body 2 has a mobile element 7 sliding inside a tubular element 8 to which a plasma jet outlet nozzle 9 is removably fixed, by means of a ring nut 24.
The mobile element 7 is elastically pushed towards the nozzle 9 by means of a helical spring and it is moved in the opposed direction by means of a pneumatic actuator, fed by the cooling and feeding compressed fluid of device 1.
The ring nut 24 and a portion of the nozzle 9 are inside a protection sleeve 25. The device includes connection means 10, consisting of a nut screw carried out in an end portion of a cavity 12 of the mobile element 7, fit for alternatively fixing the interchangeable electrode members 4, 6.
The pneumatic striking working condition P of device 1 is achieved by fixing the first electrode member 4 to the connection means 10 and by locking the first bush member 3 between the tubular element 8 and the nozzle 9. In said working condition, the first electrode member 4 is slidably driven by the mobile element 7 inside the first bush member 3, between two conditions, a condition of contact C and a condition of maximum distance D with respect to the nozzle 9.
In an electric striking working condition E, the second bush member 5 and the second electrode member 6, fixed to the connection means 10, are rigidly blocked to the tubular element 8 by stopping the mobile element 7 in a respective condition of maximum distance DD from the nozzle 9.
An end of the tubular element 8 has a first abutment means 11 for mating a first stop means 14 of the first electrode member 4 in the maximum distance condition in the pneumatic striking operation P, and a second stop means 15 of the second electrode member 6 in the electric striking working condition E.
Said end of the tubular element 8 is further provided with a first seat 13 for the end of the first bush member 3 which is opposed to the nozzle 9 and the latter has a second seat 16 for the corresponding end of the bush members 3, 5.
The second electrode member 6 has a third stop means 17 for the end of the second bush member 5, which is opposed to the nozzle 9.
The electrode members 4, 6 are provided with respective pluralities of first radial holes 18 in flow communication with the cavity 12 through respective ducts 19 of the electrode members 4, 6, for the flow of the cooling and feeding fluid of the device 1.
The bush members 3, 5 are provided with respective pluralities of second through radial holes 20 in flow communication with an interspace between the respective electrode members 4, 6 and the nozzle 9.
The first radial holes 18 of the first electrode member 4 flow outside the latter in correspondence of an annular groove 21 facing third radial holes 22 of the first bush member 3 in every pneumatic striking working condition.
The first electrode member 4 has an annular housing 30 for a seal means 31 fit to slidably mate the inner surface of the first bush member 3, interposed between the respective radial holes second 20 and third 22.
The ring nut 24 has a plurality of radial openings 26 for the fluid flow and in communication with an interspace 27 interposed between the sleeve 25 and a surface extending at the side of the ring nut 24 and the nozzle 9.
In the variant of the body 2 of figure 9, the ring nut has a plurality of inclined openings 28 for the fluid flow, each opening having a cylindrical tapered shape, with the wider diameter portion having an outlet facing the nozzle 9.
The electrode member 6 of the variant of figure 10 is provided, at the end facing the nozzle 9, with a plurality of grooves 23 fit to support the strike of the plasma jet.
Moreover the device can be provided with further interchangeable electrode and bush members having such dimensions and shapes to operate with power supplies and/or fluid flows having different values and characteristics.
The operation of the device and of the variants simply requires the assemblage of the second interchangeable electrode 6 and bush 5 members on the body 2, in order to operate in the electric striking condition E, in association with apparatuses, which provide suitable supply power impulses at high energy for striking the plasma jet. The second bush member 5, clamped by the ring nut 24 through the nozzle 9, stops the movements of the mobile element 7 and of the electrode member 6, blocking the latter on contact with the first abutment means 11. Consequently the free end of the second electrode member 6 is locked in the respective condition of maximum distance DD from the nozzle 9; such distance is predetermined for allowing the power supply impulse, applied between the second electrode member 6 and the nozzle 9, to strike an electric arc of the plasma jet between the second electrode member 6 and the nozzle 9.
By disassembling from the body 2 the second interchangeable electrode 6 and bush 5 members and replacing them with the first interchangeable electrode 4 and bush 3 members, the device works in the pneumatic striking working condition P, in association with a respective apparatus.
In said condition, the device activation involves the entry of the pressured fluid into a cylinder of the pneumatic actuator associated with the mobile element 7, which thus is moved together with the first electrode member 4 that, sliding inside the first bush member 3, progressively translates from the condition of contact C with the nozzle 9 to the condition of maximum distance D from the latter. The first electrode member 4 and the nozzle 9 are subject by the apparatus to an electric potential difference, which causes, thanks to said progressive mutual spacing, the formation of a voltaic arc between them, fit to strike the plasma jet.
In the variant of figures 11 to 13, the device 1 includes a support means 40 with tubular shaped form, having and end fixing portion 41 to the sleeve 25. The end fixing portion 41 includes an inner thread 49 for a corresponding thread 33 of the sleeve 25.
The support means 40, made of high thermal conductivity material, has a tapered shape and the diameter of the end, which is opposed to the end fixing portion 41, is smaller than the diameter thereof.
The end of the support means 40 having the smaller diameter is provided with a window 42 facing the outlet of the plasma jet of the nozzle 9 and with a plurality of indentations 43 positioned almost radially around the external end of the window 42.
The window 42 allows the exit of the plasma and the evacuation of part of the fluid flow coming from the radial openings 26 of the ring nut 24 through the interspace 27.
The support means 40 further has a plurality of almost axial through holes 44 which set in flow communication the inner portion of the support means 40 with the outside, for evacuating the remaining part of the fluid flow coming from the interspace 27.
The support means 40 is provided with baffle means 45 consisting of an almost conical annular wall having a solid angle ranging between 20° and 60°, preferably around 45°, and whose geometric vertex is inside the device. The baffle means 45 faces the ends of the outlet through holes 44, which flow outwards.
The operation of this variant of the device 1, in the pneumatic striking operation condition P and electric striking operation condition E, provides that the operator may lean the device 1 against the part to be cut, contacting the latter by the support means 40, even in correspondence of its angles and recesses.
The indentations 43 allow the almost radial exit of the portion of the fluid flow spurting through the window 42 and of the vapors, smokes or gas produced by the cut, avoiding to perturb the plasma jet.
The outlet through holes 44, in association with the baffle means 45, allow to the remaining portion of the fluid flow to cool the support means 40 and particularly the portion thereof opposed to the end connection portion 41. The baffle means 45 divert said flow, removing it from the cutting area in order to avoid perturbations of the plasma jet.
The variant of figures 14 to 16 differs from the variant of figures 11 to 13 in that the support means 40 is constituted by a wall 47 with almost constant thickness and has a set of spacer borders 46 in correspondence of its free end.
The end portion 41 of the support means 40 is fixed to the sleeve 25 through an elastic fixed joint carried out by a longitudinal slot 48 of said support means.
The main advantage of the present invention is to provide a plasma cutting torch device with pneumatic and electric arc striking capable to operate with apparatuses having electric and pneumatic arc striking by simply replacing some modular elements.
Further advantage is to propose a torch also provided with a support means for supporting the element to be cut and provided with an efficient cooling system whose flow does not perturb the plasma jet.

Claims

Plasma cutting torch device, provided with a body (2) having a mobile element (7) sliding into a tubular element (8) to which a nozzle (9) for the plasma jet exit is removably fixed, the device is characterized in that includes at least:

first interchangeable electrode (4) and bush (3) members and second interchangeable electrode (6) and bush (5) members;

a connection means (10) for interchangeable fixing the interchangeable electrode members first (4) and second (6) and carried out in a end portion of the mobile element (7);

in a pneumatic striking working condition (P) of the device (1), the first interchangeable bush member (3) is removably locked between the tubular element (8) and the nozzle (9) and the first interchangeable electrode member (4) is fixed to the connection means (10) and is slidably moved by the mobile element (7) in the first interchangeable bush member (3), between a condition of contact (C) to the nozzle (9) and a condition of maximum distance (D) from the nozzle (9); in an electric striking working condition (E), the second interchangeable bush member (5) and the second interchangeable electrode member (6), fixed to the connection means (10), are rigidly and removably locked to the tubular element (8) so fixing the mobile element (7) in the respective condition of maximum distance (DD) from the nozzle (9).
Device according to claim 1 characterized in that an end of the tubular element (8) has a first abutment means (11) to mate a first stop means (14) of the first electrode member (4) in the condition of maximum distance in the pneumatic striking working condition (P), and has a second stop means (15) of the second electrode member (6) in the electric striking working condition (E).
Device according to claim 1 characterized in that an end of the tubular element (8) has a first seat (13) for the end of the first bush member (3) opposed to the nozzle (9).
Device according to claim 1 characterized in that the nozzle (9) has a second seat (16) for the corresponding end of the bush members (3, 5).
Device according to claim 1 characterized in that the second electrode member (6) has a third stop means (17) for the end of the second bush member (5) opposed to the nozzle (9).
Device according to claim 1 characterized in that the connection means (10) consists of a nut screw carried out in an end portion of a cavity (12) of the mobile element (7) for the fluid flow; the electrode members (4, 6) being provided with respective pluralities of first radial holes (18) sets in flow communication with said cavity (12) through respective ducts (19) of the electrode members (4, 6).
Device according to claim 1 characterized in that the bush members (3, 5) are provided with respective pluralities of second radial through holes (20), in flow communication with an interspace between the respective electrode members (4, 6) and the nozzle (9).
Device according to claims 6 characterized in that the first radial holes (18) of the first electrode member (4) flow outside the latter in correspondence of an annular groove (21) facing third radial holes (22) of the first bush member (3) in each pneumatic striking working condition.
Device according to claims 7 and 8 characterized in that the first electrode member (4) has an annular housing (30) for a seal means (31) fit to slidably mate the inner surface of the first bush member (3), interposed between the respective radial holes second (20) and third (22).
Device according to claim 1 characterized in that the end of the second electrode member (6) facing the nozzle (9) has a plurality of grooves (23).
Device according to claim 1 characterized in that the body (2) has a ring nut (24) for blocking the nozzle (9) and a sleeve (25), fit for containing the ring nut (24) and, at least partially, the nozzle (9).
Device according to claim 11 characterized in that the ring nut (24) has a plurality of radial openings (26) for the fluid flow and in communication with an interspace (27) positioned between the sleeve (25) and a surface extending at the side of the ring nut (24) and of the nozzle (9).
Device according to claim 11 characterized in that the ring nut (24) has a plurality of inclined openings (28) for the fluid flow and each one having an outlet end facing the nozzle (9).
Device according to claim 13 characterized in that each inclined opening (28) has a cylindrical tapered shape with the wider diameter portion having the outlet facing the nozzle (9).
Device according to claim 1 characterized in that includes a support means (40) with shaped form having a free end fit to mate a part to be cut.
Device according to claim 15 characterized in that the support means (40) has tubular shape and has an end fixing portion (41) to the sleeve (25) which is opposed to the free end, the latter having a diameter smaller than the end fixing portion (41).
Device according to claim 15 characterized in that the support means (40) has a window (42) facing the plasma jet exit of the nozzle (9) and provided with a plurality of indentations (43).
Device according to claim 15 characterized in that the support means (40) has a plurality of almost axial outlet through holes (44) which set in flow communication the inner portion of the support means (40) with the outside.
Device according to claim 18 characterized in that the support means (40) is provided with baffle means (45) facing the ends of the outlet through holes (44) flowing outside.
Device according to claim 19 characterized in that the baffle means (45) consist of an almost conical annular wall having a solid angle ranging between 20° and 60°, preferably of around 45°, and whose geometric vertex is inside the device.
Device according to claim 15 or claim 16 characterized in that the free end of the support means (40) has a set of spacer borders (46).
Device according to claim 21 characterized in that the support means (40) is constituted by a wall (47) with almost constant thickness.
Device according to claim 16 or claim 21 characterized in that the end portion (41) of the support means (40) is fixed to the sleeve (25) by means of threads (33, 49).
Device according to claim 16 or claim 21 characterized in that the end portion (41) of the support means (40) is fixed to the sleeve (25) by means of a fixed joint.
Device according to claim 24 characterized in that the support means (40) has a slot (48) for the elastic fixed joint to the sleeve (25).