Plasma torch with snap-fit connection device for an electrode

Abstract

A plasma torch is provided with a snap-fit connection device for an electrode and comprises at least one electrical power supply means (3) for the electrode (5). The device (1) comprises a first connection element (9) and a second connection element (11) mutually fixable and detachable in a reversible and repeatable manner to place them (9, 11) in mutual mechanical and electrical connected (F) and disconnected (S) conditions. One of such first (9) or second (11) connection elements is attached to a distal end of the power supply means (3) and the other (11, 9) is attached to a proximal end of the electrode (5).

Description

[0001] PLASMA TORCH WITH SNAP-FIT CONNECTION DEVICE FOR AN

[0002] ELECTRODE

[0003] DESCRIPTION

[0004] TECHNICAL FIELD

[0005] This invention relates to the field of plasma cutting and specifically relates to a plasma torch with a snap-fit connection device for an electrode, particularly, but not exclusively, suitable for torches used with servo-operated or automated cutting equipment such as those incorporating plotters and / or robotic arms for torch movement and operation.

[0006] PRIOR ART OF THE INVENTION

[0007] Plasma torches require frequent replacement of consumable parts, particularly electrodes. Removing the electrode typically requires unscrewing the nozzle from the rest of the torch and removing it, possibly along with the insulating ring or other parts. Usually, removing the nozzle and its associated parts releases the electrode, which can be removed or falls by gravity if the torch is oriented downward. Such orientation is the usual orientation for plasma torches used in automatic cutting systems when resting inoperative for maintenance.

[0008] A disadvantage of these known plasma torches, particularly those used in automatic cutting equipment, is the risk of the electrode falling during removal, with the danger of it potentially hitting or interfering with equipment or machinery located below or nearby.

[0009] Another disadvantage of these known plasma torches is the difficulty in installing the replacement electrode, with the risk of it falling and damaging both the electrode and nearby equipment and machinery.

[0010] A further disadvantage of some known torches is that they may provide unstable or insufficient electrical contact between the electrode and its power supply, with the risk of overheating due to the Joule effect and damaging the torch.

[0011] In other types of plasma torches, the electrode is instead fixed to the torch, usually by screwing.

[0012] These torches have the disadvantage that electrode replacement is laborious, requiring unscrewing and screwing in, which is often difficult or requires special tools. Further disadvantage of these torches consists in that, once unscrewed or before being screwed, the electrode can fall if the torch is mounted vertically downward.

[0013] SUMMARY OF THE INVENTION

[0014] An object of the present invention is to provide a plasma torch with a snap-fit connection device for an electrode that retains the electrode in a loose and easily detachable manner, even when the nozzle is removed from the torch so as to allows a maintenance worker carrying out maintenance on the downward-facing plasma torch to first remove the nozzle by unscrewing it and then, even manually, detach the electrode from the torch.

[0015] Another object of the present invention is to propose a snap-fit device that allows the operator to insert a new electrode into its correct position in the torch and then to screw the nozzle, without having to worry about the torch's orientation or the risk of the electrode falling.

[0016] A further object is to propose a connection device capable of ensuring excellent electrical contact between the electrode and its power supply means.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The characteristics of the invention are highlighted below with particular reference to the attached drawings in which: - figures 1 and 2 show axonometric views of the connection device for an electrode of the plasma torch object of the present invention in the connected and disconnected conditions, respectively;

[0019] - figure 3 shows a partial cross-sectional view according to an axial plane of the plasma torch provided with the device of figure 1;

[0020] - figures 4-7 show partially sectioned views of the device of figure 1 in a sequence of passage from the connected to the disconnected condition.

[0021] BEST MODE TO CARRY OUT THE INVENTION

[0022] With reference to figures 1-7, numeral 1 indicates the snap-fit connection device for an electrode of the plasma torch object of the present invention.

[0023] The torch comprises a body in which at least one power supply means 3 is fixed, which is connected upstream to an electrical power supply for the torch, and has an opposite distal end positioned at, or otherwise accessible from, a connection portion of the torch. This connection portion is assigned to support a tip, a cartridge, or a set of consumable elements used to produce and deliver plasma during cutting.

[0024] More specifically, the power supply means 3 is assigned to be electrically connected to an electrode 5 of such tip, cartridge, or set, to conduct the electrical energy required for operation to the electrode 5 itself.

[0025] The device 1 comprises a first connection element 9 and a second connection element 11 that can be mutually fastened and detached in a reversible and repeatable manner to place the first connection element 9 and the second connection element 11 respectively in a mutual connected condition F or in a mutual disconnected condition S, where the connection or disconnection is both mechanical (for mutual fastening and disengagement) and electrical.

[0026] One of such first connection element 9 or second connection element 11 is attached, i.e., connected, fixed, or otherwise operatively associated, to the distal end of the torch's power supply means 3, and the other second connection element 11 or first connection element 9 is attached to a proximal end of the electrode 5. In the connected condition F, therefore, the proximal end of the electrode 5 is mechanically coupled and electrically connected to the distal end of the power supply means 3.

[0027] To achieve the snap-fit connection, the first connection element 9 is concave and the second connection element 11 is convex. Alternatively, some torch variants provide that the first connection element 9 is convex and the second connection element 11 is concave.

[0028] Reference will be made below to the preferred embodiment specifically illustrated in the figures, in which the first connection element 9 is concave and attached to the distal end of the power supply means 3 and the second connection element 11 is convex and attached to the proximal end of the electrode 5.

[0029] It is, however, intended and provided by the invention that the same or similar characteristics are validly included in the present description and equally applicable also in other combinations in which the first connection element 9 and the second connection element 11 are convex and concave, respectively, or attached to the electrode 5 and to the power supply means 3, or, in other words, that the same considerations described below are equally part of the present description by interchanging the first connection element 9 and the second connection element 11.

[0030] The first concave connection element 9 is preferably internally provided with at least one undercut member 13, preferably with a plurality of undercut members 13. Each undercut member 13 is hollow, i.e., it has a concavity facing the longitudinal axis A of the power supply means 3 and the first connection element 9 itself, where at least in the connected condition F these longitudinal axes A coincide.

[0031] The second convex connection element 11 is provided externally with preferably one, but possibly more, protruding members 15 of a rounded or in relief shape, the shape of each being complementary to a corresponding undercut member 13. More specifically, the second convex connection element 11 is preferably spindle- shaped, olive-shaped, barrel-shaped, truncated cone-shaped, or two truncated cones joined together at their respective larger bases, or similar shapes. Correspondingly, the cavity of the first concave connection element 9 is almost complementary in shape to that of the second convex connection element 11.

[0032] The wall of the first concave connection element 9 is made of a combination of shapes and materials that makes it elastically deformable and preferably has a plurality of cuts 10 parallel to the direction of translation of the electrode 5 in the passage between the connected F and disconnected S conditions, i.e., parallel to the longitudinal axis A of the power supply means 3. The cuts 10 divide such wall of the first connection element 9 into an equal number of flaps 8 or wings that protrude from the distal end of the power supply means 3, each flap 8 having a respective concavity that creates a respective undercut member 13.

[0033] It follows that the undercut members 13 and the protruding member 15 are constituted by the annular portions of the largest diameter of the internal face and of the external face of the first connection element 9 and of the second connection element 11, respectively.

[0034] Preferably, the undercut members 13 and the protruding member 15 made from such annular portions are placed or housed in the median portions of the first connection element 9 (i.e., in the median portion of each flap 8) and of the second connection element 11, respectively. The geometric planes on which the annular portions of the undercut members 13 and of the protruding member 15 lay, are perpendicular to the longitudinal axes of the power supply means 3 and of the electrode 5, and therefore of the first connection element 9 and of the second connection element 11. Such longitudinal axes are also parallel to the main translation direction that the electrode 5 follows in the passage between the connected F and the disconnected S conditions.

[0035] The number of cuts 10 and, consequently, of flaps 8 in the wall of the first connection element 9 is at least two and preferably not more than sixteen, taking into account that as the number of cuts 10 increases, the surface area of the flaps 8 that actually provide the mechanical coupling and electrical contact between the power supply means 3 and the electrode 5 is reduced. More preferably, such number is between five and nine, and surprisingly, an excellent compromise between mechanical coupling, elasticity, and electrically conductive surface is provided by six flaps 8, that is six undercut members 13, arranged in a circle and angularly equidistant around the longitudinal axis A of the first connection element 9, having the same dimensions and separated by six identical cuts 10 that are thin compared to the angular dimension of the flaps 8.

[0036] The longitudinal section of the wall of the first concave connection element 9 at a flap 8 or undercut member 13, i.e., the section along a plane parallel to the longitudinal axis A of the first connection element 9 and passing through the midline of the flap 8 itself, as shown for example in figure 3, preferably has the following characteristics:

[0037] - proceeding distally from the distal end of the power supply means 3, the external surface of the flap 8 remains parallel to the longitudinal axis A or diverges (possibly only locally, being cylindrically symmetrical) by an angle preferably less than 20°, preferably between 5°-15°, more preferably 10° or approximately 10°;

[0038] - proceeding distally from the distal end of the power supply means 3, the internal surface of the flap 8 initially diverges from the longitudinal axis A by an angle preferably less than 20°, more preferably about 10°, then at the widest annular portion of the undercut members 13 it returns parallel to the longitudinal axis A, and subsequently converges in the direction of the longitudinal axis A by an angle preferably less than 20°, more preferably about 10°, even more preferably 7° or about 7°, up to a distal edge or opening 19 of the first connection element 9.

[0039] Regarding the longitudinal section of the second connection element 11, however, moving away from the proximal end of the electrode 5, the external wall of the second connection element 11 preferably initially diverges from the longitudinal axis A by an angle preferably less than 20°, more preferably about 10°, even more preferably 5° or about 5°, realigns with the longitudinal axis A at the annular portion with the largest diameter, and then proceeds to converge towards the longitudinal axis A with an inclination preferably less than 20°, preferably 10° or slightly less.

[0040] In this way, in the connected condition F, the external wall of the second connection element 11 pushes against the opposed spring force by the internal wall of the first connection element 9.

[0041] Such combination of characteristics provides the flaps 8 with sufficient elasticity to open slightly as the convex second connection element 11 passes between the connected F and disconnected S conditions and, at the same time, the spring force applied by the flaps 8 of the first connection element 9 on the second connection element 11 in the connected condition F is sufficiently high to ensure that the snap-fit connection is sufficiently robust and the contact between the first connection element 9 and the second connection element 11 is continuous and uniform, even in the event of impacts or sudden movements of the torch.

[0042] The wall of the first concave connection element 9 is made of one or more materials that simultaneously exhibit excellent electrical conductivity and good flexibility under strength to allow the connection and disconnection of the first connection element 9 and the second connection element 11. Preferably, the wall of the first concave connection element 9 is made of, or based on, phosphor bronze, copper, copper-based alloy, or another metal or alloy.

[0043] Preferably, the first connection element 9 and the second connection element 11 are made as a single body with the power supply means 3 and the electrode 5, respectively, or vice versa with the electrode 5 and the power supply means 3, respectively. This makes the connection of the connection elements 9, 11 to the respective power supply means 3 and electrode 5 extremely reliable.

[0044] Preferably, the electrode 5 provided with the second convex connection element 11 is also provided with an annular shelf element 17 or collar protruding near or at the base of said second connection element 11. The annular shelf element 17 is assigned, in the connected condition F, to abut the distal edge or opening 19 of the first connection element 9, which is concave and attached to, or part of, the power supply means 3. The pair of the annular shelf element 17 and the distal edge 19 further increases the contact surface for electrical conduction in the connected condition F.

[0045] With particular reference to figures 4-7, the operation of the torch provided with the snap-fit connection device 1 described requires that, starting from the connected condition F, an operator or user of the torch pulls the electrode 5 in the direction of the longitudinal axis A. The sliding of the annular portion with the largest diameter of the second convex connection element 11 on the internal walls of the first concave connection element 9 causes the undercut members 13, i.e. the flaps 8, to open, with a widening of the distal edge 19. Once the second connection element 11 has been completely extracted from the seat formed by the first connection element 9, the undercut members 13 come closer together or close into the rest position, creating the disconnected condition S and releasing the electrode 5 from the power supply means 3.

[0046] The insertion of the second connection element 11 into the first connection element 9 proceeds in the opposite direction, obtaining the connected condition F and the attachment of the electrode 5 to the power supply means 3.

[0047] Optionally, the first connection element 9 and the second connection element 11 are such that, in the connected condition F, an end surface 12 at the proximal end of the second concave connection element 11 itself abuts against a base (not shown) at the distal end of the power supply means 3, resulting in increased electrical conduction.

[0048] To facilitate the insertion of the second convex connection element 11 into the first concave connection element 9, the distal edge 19 of the latter preferably has a countersink or recess made on its internal part, i.e., facing the longitudinal axis A while, in the variants where the end surface 12 of the second connection element 11 is almost flat, its edge is preferably slightly bevelled.

[0049] A variant of the torch provides for the first concave connection element 9 to comprise a set of curved or arched, elastic leaf spring elements that enclose a volume complementary to or slightly smaller than that of the protruding member 15 of the second convex connection element 11. Each leaf spring element is preferably associated with a respective undercut element 13, protruding from the latter's concavity. Thus, in the connected condition F, such leaf spring elements push elastically against the convex surface of the second connection element 11, maintaining electrical contact and mechanical constraint with the electrode 5.

[0050] In a second embodiment, not illustrated, of the plasma torch with a snap-fit connection device for an electrode object of the present invention, each undercut member 13 is shaped like a hemisphere, i.e., a sector of a sphere, cylinder, or slot obtained in the cylindrical or prismatic wall, as already described, of the first concave connection element 9 (or of the second connection element 11 if it is the concave one), starting from the internal face of the latter.

[0051] The opposite second convex connection element 11 has, for each undercut member 13 of the first concave connection element 9, a protruding member 15 in the shape of a small sphere, a raised lip, or a wing, chamfered and elastically held protruding with respect to the convex face or surface of the cylindrical or prismatic shape of the second convex connection element 11 itself.

[0052] Such undercut 13 and protruding 15 members are complementary or approximately complementary, and are mutually and reversibly engaged in the mutual connected condition F.

Claims

AMENDED CLAIMS received by the International Bureau on 15 January 2026 (15.01.2026)1) Plasma torch with snap-fit connection device for an electrode comprising at least one electrical power supply means (3) for the electrode (5); said device (1) comprises a first connection element (9) and a second connection element (11) which can be mutually fixed and detached in a reversible and repeatable manner to place them (9, 11) in conditions of mutual mechanical and electrical connection (F) and disconnection (S), wherein one of such first (9) or second (11) connection elements is attached to a distal end of the power supply means (3) and the other (11, 9) is attached to a proximal end of the electrode (5), said first connection element (9) is of the concave type and the second connection element (11) is of the convex type or vice versa and the concave type connection element (9, 11) is internally provided with at least one concave undercut member (13) and that the convex type connection element (11, 9) is externally provided with at least one protruding member (15) each having a shape complementary to a corresponding undercut member (13); said torch being characterized in that the at least one undercut member (13) is in the shape of a hemisphere, cylinder or slot obtained in the cylindrical or prismatic shaped wall of the concave type connection element (9, 11) starting from the internal face of the latter, and that the convex type connection element (11, 9) has, for each undercut member (13) of the concave connection element (9, 11), a protruding member (15) in the shape of a sphere, lip or fin chamfered and kept elastically protruding with respect to the cylindrical or prismatic shaped face of the convex connection element (9, 11); wherein said undercut members (13) and protruding members (15) are mutually and reversibly engaged in the connected condition (F); said electrode (5) is provided with the second connection element (11) of the convex type and with an annular shelf element (17) protruding in the proximity of said second connection element (11) and assigned, in the connected condition (F), to abut with a distal edge or opening (19) of the first connection element (9) of the concave type of the power supply means (3).2) Torch according to claim 1 characterized in that the convex type connection element (11, 9) is in the shape of a spindle, olive, barrel, truncated cone or two truncated cones joined at their larger base and the cavity of the concave type connection element (9, 11) has a shape almost complementary to that of the convex connection element (11, 9), wherein the wall of the concave connection element (9, 11) is elastically deformable and has a plurality of cuts (10) parallel to the direction of translation of the electrode (5) in the passage between the connected (F) and disconnected (S) conditions, or the concave connection element (9, 11) comprises a set of leaf spring elements that enclose a volume complementary to that of the convex connection element (11, 9).3) Torch according to claim 1 or 2 characterized in that the undercut (13) and protruding (15) members are constituted by the annular portions of the largest diameter of the internal and external faces of the concave and convex connection elements (9, 11) respectively.4) Torch according to claim 3 characterized in that the undercut (13) and protruding (15) members are placed in the central portions of the connection elements (9, 11) the longitudinal axes of which are perpendicular to the geometric planes to which the undercut (13) and protruding (15) members belong and, in the passage between the connected (F) and disconnected (S) conditions, such longitudinal axes are parallel to the direction of translation of the electrode (5).5) Torch according to any one of the preceding claims characterized in that the wall of the concave connection element (9, 11) is made of phosphor bronze or another metal.6) Torch according to any of the preceding claims characterized in that the first connection element (9) and the second connection element (11) are made in a single body respectively with the power supply means (3) and the electrode (5), or vice versa.

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