EP0599709B2 - Plasma cutting torch - Google Patents

Description

The present invention relates to cutting torches plasma, of the type comprising a torch body comprising an electrode and a nozzle, and means mounting and connecting the torch body.

Plasma cutting torches typically include a monobloc torch body with, at the back connections to supply lines in fluid and electrical energy and fixing means on a frame or a working machine, and in the front, means for mounting the electrode and the nozzle. Disassembly of these torches, for maintenance operations or replacement of worn or defective parts, requires disassembly operations and winding delicate and long, which immobilize the production machine for a long time and which most often oblige to proceed to new torch positioning settings before reviving the production.

GB-A-2091594 discloses a modular torch comprising a received cathode subassembly in a nozzle subassembly, these two subassemblies being arranged prisoners in a subset of box in several parts.

Moreover, there are other documents of the prior art, which can be refer to, which describe plasma torches composed of several parts to be fixed to each other, namely in particular JP-U-60-5989, EP-A-0079019 and JP-A-01-118374.

In addition, US-A-4,756, 686 teaches a manual brazing torch or the like comprising a ball cage mechanism for to allow a connection of the nozzle on the torch body.

Similarly, EP-A-326,445 describes a plasma arc torch on which just plug in a cartridge made of a electrode and a nozzle. The cartridge is fixed in the torch body via a cage type mechanism.

The object of the present invention is to propose a new torch architecture, modular design, allowing a quick and easy replacement of the body torch and / or its constituent elements and suppressing positioning re-adjustment problems after reassembly.

To do this, according to the invention, the torch comprises a torch holder comprising a first series of fluid passages connectable to respective circuits supplying said fluids and a first face of support, a unitary set of torch bodies comprising an electrode and a nozzle and having a second set of fluid passages and a second support face, and assembly means for assembling quickly the unitary set of torch body and the torch stand, with the first and second bearing faces in axial support against each other and with the passages from the first series communicating with the respective passages of the second series as defined in claims 1, 2 or 3.

• au moins un des passages de fluide de la deuxième série comporte une partie d'extrémité faisant saillie par rapport à la deuxième face d'appui et destinée à être reçue dans un logement du support définissant une partie d'un passage de la première série ;
• la première et la deuxième séries de passages comportent chacune :
  • un passage de gaz plasmagène,
  • au moins un passage de fluide de refroidissement,
• l'ensemble de corps de torche comprend au moins un piston de déplacement relatif de l'électrode par rapport à la tuyère, les première et deuxième séries de passages comportant chacune au moins un passage de gaz d'actionnement du piston,
  l'ensemble de corps de torche comprend un premier moyen à actionnement par fluide de maintien de l'électrode et, avantageusement, un deuxième moyen à actionnement par fluide de maintien de la tuyère.

According to other features of the invention:

• at least one of the fluid passages of the second series has an end portion projecting from the second bearing face and intended to be received in a housing of the support defining a portion of a passage of the first series;
• the first and second series of passages each comprise:
  • a passage of plasma gas,
  • at least one cooling fluid passage,
• the torch body assembly comprises at least one relative displacement piston of the electrode with respect to the nozzle, the first and second series of passages each comprising at least one actuating gas passage of the piston,
  the torch body assembly comprises first fluid holding means for holding the electrode and, preferably, a second fluid holding means for holding the nozzle.

• la figure 1 est une vue schématique, en élévation, d'une torche selon l'invention ;
• les figures 2 et 3 sont des vues en coupe longitudinale, du support de torche et du corps de torche de la torche de la figure 1, respectivement ; et

Other features and advantages of the present invention will emerge from the following description of embodiments, given by way of illustration but not by way of limitation, with reference to the accompanying drawings, in which:

• Figure 1 is a schematic elevational view of a torch according to the invention;
• Figures 2 and 3 are longitudinal sectional views of the torch holder and the torch body of the torch of Figure 1, respectively; and

FIG. 4 is a longitudinal sectional view of an embodiment of a torch according to the invention.

In the description that follows and on the drawings, identical or similar elements bear the same reference numbers, possibly indexed.

A plasma cutting torch according to the invention comprises, in general, a torch holder A, intended to be mounted on a machine frame and on a end of which is mounted a unitary set of torch body B, the torch holder A comprising, at its opposite end, a series C of connecting elements to fluid lines and lines electric.

In the embodiment shown in the figures 1 to 3, the torch holder A has a block metal 1, typically made of brass, having a succession of stepped bores of different diameters 2. 3, 4, 5 and surrounded by an insulating envelope 6. In the larger diameter bore 2 open a passage supply of cooling gas 7 and a passage supply gas supply 8. Connection between bores 2 and 3 form an annular face transverse 9 in which a passage opens supplying a second actuating gas 10. In the bore 3 opens a passage 11 of supply of a third actuating gas. In the bottom of the bore 4 is mounted an electrical contact socket 5, the bore 4 communicating with a tubing T of gas supply plasma. Support A has, at its end before, a metal sleeve 12 isolated from the block 1 and comprising an external thread 13.

As seen in Figure 3, the torch body B comprises a metal tubular assembly 14 comprising a rear part forming a sliding piston 15 in an internal bore 16 of a metallic tubular jacket 17 provided with peripheral seals and intended to be received in the first bore 2 of the support of torch A. The shirt 17 is secured to a set lower skirt 18 whose upper end forms a flange 19 extending radially outwardly. On the lower end of the skirt set 18 is mounted a cap 20. The tubular assembly 14 is extended rearwards by a stepped cylindrical part intended to be received sealingly in the bores rear 3 and 4 of the torch holder A. The rear end of the liner 17 forms an annular bearing surface 21 coming against the annular face 9 of the support torch A. In the tubular assembly 14 is mounted sealingly a tubular element 22 enclosing a spring 23 urging downward on a sliding piston 24 in a sealed manner in the tubular element 22 and secured a hollow rod 25 extending with a leaktight sliding in the tubular element 22 and in a tubular extension 33 of the assembly 14, and carrying, at its end lower, a longitudinal tongs clamp structure flexible means 26 forming locking means and maintaining a hollow electrode tail 27 carrying its lower end a hollow electrode 28. The clip structure 26 cooperates with a clip lock outer tubular 29 slidably mounted on the rod 25 and resiliently biased downwards by a spring 30. The latch 29 has at least one transverse protrusion 31 through an oblong slot 32 formed in the tubular extension 33 of the assembly 14 and carrying, at its lower end, a clamp structure 34 with cooperating flexible longitudinal tongues with a peripheral elastic ring 35 and forming means for holding and blocking a nozzle 36 in which extends the electrode 28 and provided centrally a plasma jet ejection channel 37.

In the assembled position of the torch body B in the support A, the plasma gas introduced into the bore 4 crosses the torch body B centrally in the electrode 28 from which it passes inside the nozzle 36. The cooling gas introduced into the passage 7 penetrates, through transverse openings 38 into the shirt 17 to flow into the skirt 20, around the nozzle 36. A locking gas, introduced through passage 8, penetrates through transverse openings 39, in the bore 16 to push back the piston 15 up and hold the clamps 26 and 34 in the configuration engagement of electrode tail 27 and the nozzle 36, respectively. The upper part 40 of the assembly 14 forms, in the bore 3, an unlocking piston which, when unlocking gas is introduced into the bottom of the bore 3 through the passage 11, pushes the assembly 14 downward, thus releasing the clamp structure 34 of the ring 35 and allowing the extraction of the nozzle 36. Before the unlocking piston 40 does not reach the end of the race, the projections 31 abut on an internal shoulder 41 of the sleeve 17, thus releasing the clip 26 and allowing the release of the electrode 28. The electrode 28 is normally kept pressed against the bottom of the nozzle 36 by the spring 23. To realize the ignition of the arc, in start of operating phase, priming gas is introduced through the passage 10 and enters through passages transverse, 42 between the set 14 and the set 22 into an annular chamber 43 in front piston 24 to push the latter against the spring 23 and thus discard the electrode 28 of the nozzle 36 for, at first, to start the bow and, by following, allow the escape of the plasma gas since inside the nozzle 36 to the outside, through the passage 37.

As seen in Figure 1, the torch body B is kept locked on the support A by a nut 70 cooperating with the flange 19 and screwed on the thread 13 of the support A, a simple unscrewing of the nut D allowing to extract the torch body assembly B for a quick replacement of the latter.

In the embodiment of FIG. the insulating envelope 6 and the metal block 1 of the Torch support A, which has, here, a lower face flat transverse 9 forming support for the bottom 21 of a ball cage 45 forming the rear end of a block 46 of the torch body B which encloses a structure of hollow electrode 280 protruding rearward and on the lower end or front of which is mounted the nozzle 36 surrounded here in a sealed manner by a skirt 20 'defining part of a cooling circuit water, the water being introduced into a longitudinal passage 47 in block 1, passing through a passage 48, aligned with the passage 47, in the block 46, into the cap 20 'to pass, via transverse passages 49, inside the electrode structure 280 and come out up block 1 through an exit passage 50. The electrode structure 280 extends upward, beyond of the face 21, in a central stepped bore 51 of the block 1 having an electrical contact socket 52. The electrode structure 280 further forms a structure intermediate piston 53 sliding in a bore central block 46, the front face of the piston 53 receiving, by aligned passages 54 in block 1 and 55 in block 46, a priming gas to move the electrode 280 of the nozzle 36, a defusing gas being introduced, by a passage opening, in 56, on the face rear of the piston 53 to bring back, at the end of use and at the beginning of reuse, the electrode 280 in contact with the nozzle 36 where the plasma gas arrives through passages opening radially, at 57, in the nozzle 36.

As seen in Figure 4, the passages of fluids, such as 48 and 55, of the torch body B, comprise sockets, such as 58 and 59, projecting beyond of the face 21 and received sealed in the passages corresponding, such as 54, of the torch holder. The socket 58 of the cooling water supply circuit cooperates with a hollow rod 60 arranged in the passage supply of water 47 to repel, in use, a shutter valve 61 biased elastically in position closure. Similarly, the passage water outlet 50 comprises, at the outlet, a key 62 normally elastically biased towards its position closing and open, in assembled configuration, by the upper, hollow end of the electrode structure 280. In this way, by disconnecting the body from torch B of the torch holder A, the valves 61 and 62 are close, thus avoiding the flow of water since torch bracket A.

In the embodiment shown in the figure 4, the cage 45 carries at least one ball 63 intended to cooperate, in blocking position, with an annular groove 64 formed at the periphery of the cylindrical front end from block 1 and with a sliding cylindrical lock 65, forming a ramp, arranged in a chamber of the end before the insulating casing 6 and urged in position locking by a spring 66. The torch body B has a sliding pusher 67 allowing to retract the lock 65, against the spring 66, when of set up, by simple plugging, and extraction Torch body B.

Claims (12)

1. Plasma cutting torch comprising:

   a torch support (A) comprising a metal block (1) with a first series of fluid passages (7, 8, 10, 4, 47, 50, 54) which can be connected to respective circuits for the said fluids, and a first bearing face (9);

   a unitary torch body assembly (B) comprising an electrode (28, 280) and a nozzle (36) and comprising a second series of fluid passages (25, 27, 38, 39, 42, 48, 49, 55, 56) and a second bearing face (21); and

   assembly means (D) for rapidly assembling the unitary torch body assembly on the torch support, with the first and second bearing faces bearing axially against one another, and with the passages of the first series communicating with the respective passages of the second series,

   characterized in that the assembly means (D) are of the quick locking type with a ball cage (45, 63, 65), and the cage (45) carries at least one ball (63) intended to cooperate, in the blocking position, with an annular groove (64) formed at the periphery of the cylindrical front end of the block (1) and with a sliding cylindrical locking element (65), forming a ramp, arranged in a chamber in the front end of an insulating casing (6) surrounding the block (1) and urged into the locking position by a spring (66), the torch body (B) comprising a sliding pusher (67) enabling the locking element (65) to be retreated, against the action of the spring (66), during the fitting of the torch body (B) by plugging it in and during the removal thereof.
2. Plasma cutting torch comprising:

   a torch support (A) comprising a first series of fluid passages (7, 8, 10, 4, 47, 50, 54) which can be connected to respective circuits for the said fluids, and a first bearing face (9) ;

   a unitary torch body assembly (B) comprising an electrode (28, 280) and a nozzle (36) and comprising a second series of fluid passages (25, 27, 38, 39, 42, 48, 49, 55, 56) and a second bearing face (21); and

   assembly means (D) for rapidly assembling the unitary torch body assembly on the torch support, with the first and second bearing faces bearing axially against one another, and with the passages of the first series communicating with the respective passages of the second series,

   at least one of the fluid passages of the second series comprising an end portion (40, 58, 59) projecting with respect to the second bearing face (21) and intended to be accommodated in a housing (3; 47, 54) of the torch support (A) defining part of a passage of the first series, the first and the second series of passages each comprising at least one cooling fluid passage (7, 38; 47, 50, 48, 55), the cooling passage (47; 50) of the first series of passages comprising at least one valve (61; 62) which can be actuated by the projecting end portion (58; 280) of a passage of the second series of passages.
3. Plasma cutting torch comprising:

   a torch support (A) comprising a first series of fluid passages (7, 8, 10, 4, 47, 50, 54) which can be connected to respective circuits for the said fluids, and a first bearing face (9);

   a unitary torch body assembly (B) comprising an electrode (28, 280) and a nozzle (36) and comprising a second series of fluid passages (25, 27, 38, 39, 42, 48, 49, 55, 56) and a second bearing face (21); and

   assembly means (D) for rapidly assembling the unitary torch body assembly on the torch support, with the first and second bearing faces bearing axially against one another, and with the passages of the first series communicating with the respective passages of the second series,

   characterized in that the unitary torch body assembly (B) comprises at least one piston (24; 53) for moving the electrode (28, 280) with respect to the nozzle (36), the first and second series of passages each comprising at least one passage (10; 42; 54; 55, 56) for piston-actuating gas.
4. Torch according to Claim 1 or 3, characterized in that at least one of the fluid passages of the second series comprises an end portion (40, 58, 59) projecting with respect to the second bearing face (21) and intended to be accommodated in a housing (3; 47, 54) of the torch support (A) defining part of a passage of the first series.
5. Torch according to one of Claims 1 to 4, characterized in that the first and the second series of passages each comprise a plasmagenic gas passage (4; 57).
6. Torch according to either of Claims 1 and 3, characterized in that the first and the second series of passages each comprise at least one cooling fluid passage (7, 38; 47, 50, 48, 55).
7. Torch according to either of Claims 1 and 2, characterized in that the unitary torch body assembly (B) comprises at least one piston (24; 53) for moving the electrode (28, 280) with respect to the nozzle (36), the first and second series of passages each comprising at least one passage (10; 42; 54; 55, 56) for piston-actuating gas.
8. Torch according to one of the preceding claims, characterized in that the unitary torch body assembly (B) comprises a first fluid-actuated means (26, 15) for retaining the electrode (28) in an unlockable manner.
9. Torch according to one of Claims 1 to 8, characterized in that the unitary torch body assembly (B) comprises a second fluid-actuated means (34, 15) for retaining the nozzle (36) in an unlockable manner.
10. Torch according to Claim 6, characterized in that the cooling passage (47; 50) of the first series of passages comprises at least one valve (61; 62) which can be actuated by the projecting end portion (58; 280) of a passage of the second series of passages.
11. Torch according to either of Claims 2 and 3, characterized in that the assembly means (D) comprise a nut (70).
12. Torch according to either of Claims 2 and 3, characterized in that the assembly means (D) are of the quick-lock with a ball cage (45, 63, 65).

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