Electric arc cutting or welding torch with rapid assembly system

Abstract

The invention relates to an electric arc cutting or welding torch comprising a torch body and torch head to be assembled to or disassembled from the torch body, the torch body comprising a peripheral wall and an axial housing, the axial housing comprising an orifice for receipt of at least part of the torch head, an actuator which is mobile in translation in the axial housing, at least one blocking element which is fitted so as to be mobile on the peripheral wall, the blocking element and the torch head each comprising reciprocal engagement means, the actuator being configured to maintain the blocking element spaced relative to the peripheral wall, the actuator also being configured to be displaced in the axial housing when the torch head is inserted in the orifice.

Claims

1. An electric arc cutting or welding torch comprising a torch body and torch head which is able and designed to be assembled to or disassembled from the torch body, the torch body comprising: a peripheral wall and an axial housing, the axial housing comprising an orifice for receipt of at least part of the torch head; an actuator which is mobile in translation in the axial housing in the axial direction; at least one blocking element which is fitted so as to be hingedly mobile on the peripheral wall, the blocking element and the torch head each comprising a corresponding locking mechanism to limit axial displacement of the torch head within the torch body; the actuator being configured to maintain the blocking element spaced relative to the peripheral wall, so as to permit the insertion of the torch head in the orifice; and the actuator also being configured to be displaced in the axial housing when the torch head is inserted in the orifice, so as to enable the blocking element to be brought towards the peripheral wall until the blocking element and the torch head engage.

2. The torch of claim 1, wherein the blocking element is connected to the peripheral wall of the torch body via a hinge, the blocking element being hingedly mobile in pivoting around the hinge.

3. The torch of claim 1, wherein said torch comprises at least two blocking elements which are distributed around the peripheral wall.

4. The torch of claim 1, wherein the blocking element comprises a stop, the actuator being configured to be supported on the stop, so as to maintain the blocking element spaced from the peripheral wall.

5. The torch of claim 4, wherein the actuator and/or the stop are formed to allow the blocking element to be brought progressively towards the peripheral wall when the torch head is inserted in the orifice in the axial housing.

6. The torch of claim 1, wherein the actuator is displaced away from the orifice when the torch head is inserted in the orifice in the axial housing.

7. The torch of claim 1, wherein said torch comprises a first elastic element which is configured to exert an elastic compression force which tends to displace the actuator in the direction of the orifice in the axial housing.

8. The torch of claim 1, wherein an outer ring forms a sleeve around at least part of the torch body, the outer ring being mobile in translation around the torch body.

9. The torch of claim 8, wherein said torch further comprises a second elastic element which is configured to exert an elastic compression force which tends to displace the outer ring in the direction of the orifice in the axial direction.

10. The torch of claim 8, wherein the blocking element cooperates with the outer ring such that, when the blocking element is spaced from the peripheral wall by the actuator, the blocking element tends to oppose the movement of translation of the outer ring in the direction of the orifice in the axial housing.

11. The torch of claim 8 wherein the blocking element cooperates with the outer ring such that the engagement of the blocking element and the torch head gives rise to the displacement of the outer ring in the direction of the orifice in the axial housing, such that the outer ring prevents disengagement of the blocking element and the torch head.

12. The torch of claim 1, wherein the blocking element cooperates with the outer ring, such that spacing of the ring from the orifice gives rise to spacing of the blocking element from the peripheral wall, and disengagement of the blocking element and the torch head, the actuator being configured to exert a force on the torch head which tends to eject the torch head from the orifice.

13. The torch of claim 1, wherein a compressible element is arranged between the torch body and the torch head.

14. The torch of claim 9, wherein said torch comprises a first elastic element which is configured to exert an elastic compression force which tends to displace the actuator in the direction of the orifice in the axial housing, wherein a ratio of a second load applied to the second elastic element, and of a first load applied to the first elastic element, is between 0.1 and 0.95.

15. An electric arc cutting or welding process in which a torch of claim 1 is implemented in order to cut or weld a metal part.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will be explained in greater detail with reference to the appended figures in which:

(2) FIG. 1 schematizes in longitudinal cross-section a plasma cutting or welding torch body according to an embodiment of the invention;

(3) FIG. 2 is a view in partial longitudinal cross-section of a torch head according to the invention assembled on a torch body according to FIG. 1; and

(4) FIGS. 3a, 3b, 3c and 3d schematize steps of the disassembly of a torch head and a torch body according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

(5) The figures of the present application schematize embodiments of the invention according to which the torch is an electric arc plasma cutting torch.

(6) It will be appreciated that the present invention is applicable for any type of cutting or welding torch which implements an electric arc.

(7) FIG. 1 schematizes the body 16 of a plasma cutting torch in a position in which it is disassembled from the torch head (not illustrated). The torch head 16 comprises a peripheral wall 1 and an electrode holder 2 which forms a cathode. The electrode holder 2 serves the purpose of conveying the electric current to the electrode of the torch head, whereas the peripheral wall 1 forms an insulating block which ensures electrical insulation between the electrode holder 2 and the element which supports the nozzle of the torch head 17.

(8) The torch body 16 comprises an axial housing 10 in which the electrode holder 2 is arranged, the axial housing 10 comprising in its downstream end an orifice 10a which is designed to receive the upstream part 17a of the torch head 17.

(9) The peripheral wall 1 and the electrode holder are kept together by means of a shaft 7 shown partly in FIG. 1, which is screwed around the peripheral wall 1.

(10) According to a preferred embodiment of the invention, the torch body 16 comprises an actuator 6 which is arranged in the axial housing 10, and is mobile in translation in the axial housing 10. Preferably, the actuator 6 is arranged between the peripheral wall 1 and the electrode holder 2. Advantageously, the actuator 6 is arranged connected mechanically to the electrode holder 2 by a slide connection.

(11) In addition, the torch body 16 comprises at least one blocking element 8 which is fitted so as to be mobile on the peripheral wall 1. According to a preferred embodiment, the blocking element 8 is fitted so as to pivot on the peripheral wall 1 of the torch body 16 via a hinge 15.

(12) Advantageously, the torch body 16 comprises a plurality of blocking elements 8 distributed around the peripheral wall 1. There are preferably at least two blocking elements 8, and ideally three of them. The maximum number of blocking elements 8 is advantageously five.

(13) According to the invention, when the torch is in the disassembled position, i.e. when the torch head 17 is disassembled from the torch body 16, the actuator 6 is configured to maintain the blocking element 8 spaced from the peripheral wall 1 of the torch body 16. Thus, as illustrated in FIG. 1, the actuator 6 exerts pressure on at least part of the inner face of the blocking element 8, so as to pivot the blocking element 8 towards the exterior of the torch, in order to space it from the peripheral wall 1.

(14) The blocking element 8 advantageously comprises a stop 81 against which the actuator 6 is supported. Preferably, the stop 81 is a projection 81 which is provided on the inner face of the blocking element 8. It is then the pressure exerted on the stop 81 which makes it possible to space the blocking element 8.

(15) According to the preferred embodiment of the invention, the torch comprises a first elastic element 3, which is configured to exert an elastic compression force which tends to displace the actuator 6 downwards, in the direction of the orifice 10a in the axial housing 10. Preferably, the first elastic element 3, for example a helical spring 3, is arranged in the axial housing 10. Advantageously, the first elastic element 3 is arranged between the actuator 6, the peripheral wall 1 and the electrode holder 2.

(16) According to a variant of the invention, the first elastic element 3 can be replaced by pressurising the volume which is delimited by the actuator 6, the peripheral wall 1 and the electrode holder 2. In other words, a pressure exists in this volume which is greater than atmospheric pressure, such as in the conventional pneumatic or hydraulic jack systems in which the excess pressure is obtained by introducing a pressurised gas or liquid into a compression chamber.

(17) Thus, in the absence of a torch head inserted in the axial housing 10, the actuator 6 can be displaced in the axial housing 10 until pressure is exerted on the inner face of the blocking element 8, advantageously at the stop 81, so as to make the blocking element 8 pivot towards the exterior, which spaces it from the peripheral wall 1.

(18) According to a particularly advantageous embodiment, the torch body 16 additionally comprises an outer ring 4 which forms a sleeve around at least part of the torch body 16. The outer ring 4 is mobile in translation around the torch body 16.

(19) Advantageously, the blocking element 8 is formed such that, when the blocking element 8 is spaced from the peripheral wall 1 by the actuator 6, the blocking element 8 tends to oppose a movement of translation of the outer ring 4 in the direction of the orifice 10a.

(20) As can be seen in FIG. 1, the pivoting of the blocking element 8 caused by the thrust of the actuator 6 thrusts the outer ring upwards, i.e. moving it away from the orifice 10a. Preferably, the displacement upwards of the outer ring 4 is limited by stop means which are preferably provided on the outer ring 4 and/or the shaft 7, which also makes it possible to limit the pivoting of the blocking element 8.

(21) FIG. 2 schematizes the assembly of a torch body according to FIG. 1 on a torch head 17. The torch head 17 comprises in a conventional manner in its lower part an electrode, a nozzle, and a protective cover (not illustrated).

(22) The blocking element 8 and the torch head 17 each comprise means 19, 20 for engagement with one another. The engagement means 19, 20 can be at least one projection 19 provided on the blocking element 8, which cooperates with an opening or groove 20 provided in the upstream part 17a of the torch head 17. In an equivalent manner, a projection 19 and an opening or groove 20 can be provided in the torch head 17 and the torch body 16 respectively.

(23) According to the invention, the actuator 6 is configured to be displaced, preferably axially, in the axial housing 10, when the torch head 17 is inserted in the orifice 10a, with the displacement of the actuator 6 bringing the blocking element 8 towards the peripheral wall 1, until the blocking element 8 and the torch head 17 engage.

(24) By design, when the blocking element 8 and the torch head 17 are engaged, the electrical contact and the fluid sealing are ensured between the head and the torch body. The torch assembly can thus be carried out in a manner which is reliable and reproducible by the operator.

(25) According to the embodiment illustrated in FIG. 2, the plasma torch is assembled by inserting the upstream part 17a of the torch head 17 in the orifice 10a until it comes into contact with the actuator 6, in order to exert on it a force which opposes and exceeds the force exerted by the first elastic element 3. The actuator 6 is then thrust upwards, which releases the blocking element 8, and allows it to approach the peripheral wall 1.

(26) Preferably, when the blocking element 8 and the torch head 17 are engaged via the engagement means 19, 20, the blocking element 8 is aligned with the peripheral wall 1, such that the blocking element 8 no longer prevents a movement of translation of the outer ring 4 in the direction of the orifice 10a. The term aligned means that the outer surface of the blocking element is positioned flush with, or recessed from, the peripheral wall 1, such that the blocking element 8 does not form, or scarcely forms, an excess thicknesses relative to the peripheral wall 1, thus permitting the translation of the outer ring 4 along the peripheral wall 1 in the direction of the orifice 10a.

(27) Thus, the blocking element 8 can be displaced between at least two positions, i.e. a so-called spaced position, in which the blocking element 8 is maintained towards the exterior, i.e. spaced from the peripheral wall 1 by the actuator 6, and a so-called close position, in which the blocking element 8 is positioned in the extension of the peripheral wall 1, and forms a substantially zero angle with the peripheral wall 1. It will be appreciated that the blocking element 8 can occupy intermediate positions between the spaced position and the close position, these intermediate positions depending in particular on the position of the outer ring 4 around the torch body 16 and/or the position of the actuator 6 in the axial housing 10.

(28) As illustrated in FIG. 1, the outer ring 4 comprises a downstream end 4a which extends according to a longitudinal direction around the axis A of the torch, and comes opposite the blocking element 8, so as to maintain it engaged with the upstream part 17a of the torch head 17. By this means, the locking of the torch assembly is ensured by the outer ring 4, which forms a sleeve around at least part of the blocking element 8. The outer ring 4 then occupies a so-called low position.

(29) Preferably, the torch comprises a second elastic element 5 which can be a helical spring, arranged so as to exert an elastic compression force which tends to displace the outer ring 4 in the direction of the downstream orifice 10a in the axial housing 10.

(30) The second elastic element 5 is preferably arranged between the outer ring 4 and the peripheral wall 1.

(31) The disassembly of the torch according to the invention advantageously takes place according to the steps illustrated in FIGS. 3a to 3d.

(32) In order to disassemble the torch head 17 from the torch body 16, the operator displaces the outer ring 4 by moving it away from the orifice 10a (FIG. 3a). The blocking element 8 is thus released from the constraint of the outer ring 4, and can pivot towards the exterior of the torch, and be disengaged from the upstream end 17a of the torch head 17 (FIG. 3b). The ejector 6, which is no longer blocked by the stop 81 of the blocking element 8, is translated towards the orifice 10a under the effect of the force exerted by the elastic element 3 (FIG. 3c). The extent of the force exerted by the elastic element is advantageously such that the torch head 17 is ejected by the orifice 10a without the operator needing to exert traction movement on the torch head 17.

(33) Optionally, the torch comprises braking means 22 which are configured to brake the movement of ejection of the torch head 17 through the orifice 10a. This prevents the risk of sudden ejection of the torch head 17, and/or makes it possible to eliminate uncertainty of the tolerance relating to the force exerted by the elastic element 3. Preferably, a compressible element 22 is arranged between the torch body 16 and the torch head 17. The compressible element 22 can be an elastomer O-ring seal, and can advantageously have a compression force which takes the form of a deformation distance of the elastomer at the torus diameter of between 0.01 and 1 mm.

(34) Within the context of the invention, it is advantageous to ensure that a first load F1 is applied to the first elastic element 3 which is greater than the second load F2 applied to the second elastic element 5. Preferably, the dimensions of the first and second elastic elements will be such that the ratio F2/F1 of the second load F2 applied to the second elastic element 5, to the first load F1 applied to the first elastic element 3, is between 0.1 and 0.95, more preferably between 0.7 and 0.8, and ideally approximately 0.75. These force ratio values make it possible to ensure that the outer ring 4 remains well in the low position in order to lock the blocking element 8.

(35) By way of non-limiting example, in the case of a ratio F2/F1 equal to 0.75, the first load F1 will be 40 N and the second load F2 will be 30 N.

(36) The present invention thus makes it possible to carry out the assembly of the torch head 17 on the torch body 16 in a reliable and robust manner, whilst providing the operator with good longitudinal positioning. In addition, the assembly and disassembly of the torch head 17 relative to the torch body 16 is simple and rapid, since it requires a minimum number of actions by the operator, i.e. assembly by inserting the head 17 in the body 16 so as to exert a thrust on the actuator 6, and disassembly by raising the outer ring 4.