Component of a plasma arc torch and method of operating a component of a plasma arc torch

Abstract

An assembly for a plasma arc torch, comprising: an electrical contact element (6) having a proximal contact surface (25) for contact with a power supply part (8) and a cavity having an inner side wall for contact with a side wall of a proximal end portion (14) of an electrode (3); a spring (4) for urging the electrode (3) away from the electrical contact element (6); and an insulating element (5) arranged on the electrical contact element (6) and adapted to prevent a current transfer from the electrical contact element (6) to the spring (4).

Description

Technical Field

[0001] This invention relates to an assembly for contact-activated plasma arc welding torch, the assembly comprising an electrical contact element for conducting current from a power supply element to an electrode, and a spring for pushing the electrode in a direction away from the power supply element. The invention also relates to a method of operating the assembly of the plasma arc welding torch. Background Technology

[0002] Plasma arc welding torches with movable electrodes are well known in the art. These movable electrodes are biased towards a forward position by a spring, with the distal end of the electrode contacting the nozzle. A current is applied to the electrode, which is then moved to a rearward position by the action of plasma gas introduced into the plasma chamber, thereby forming a guiding arc between the electrode and the nozzle. The guiding arc is then transferred from the nozzle to the workpiece to be processed.

[0003] Among these known solutions, there is a problem: ensuring that current is delivered from the power source to the electrode when the electrode is in the front position, especially during its movement from the front position to the rear position.

[0004] For example, Czech Patent No. 304595 discloses a component in which a contact element is used to perform the transfer, the contact element being arranged on a spring for pushing an electrode to a forward position, wherein during the movement from the forward position to the rear position, current flows through the spring and the contact element or through an inserted conductor in the form of a wire.

[0005] In EP3152984, the spring used to push the electrode to the front position is fixed such that the spring generates torque during the process of moving to the rear position, wherein the torque causes the side surface of the contact element to push toward the side surface of the electrode, which ensures that they are in contact even during the process of moving from the front position to the rear position.

[0006] The disadvantage of these devices is the spring stress caused by the large current required for the plasma arc, which can damage and degrade the springs, manifesting as corrosion or tempering. Summary of the Invention

[0007] The aforementioned drawbacks of existing welding torches are eliminated by components of a plasma arc welding torch, which include:

[0008] An electrical contact element has a proximal contact surface and a cavity, the proximal contact surface being used to contact a power supply component, and the cavity having an inner sidewall for contacting a sidewall of a proximal portion of an electrode;

[0009] A spring, used to push the electrode away from the electrical contact element; and

[0010] An insulating element is placed on the electrical contact element and is adapted to prevent current from being transmitted from the electrical contact element to the spring.

[0011] The assembly may also include an electrode, wherein a proximal portion of the electrode is insertable into a cavity of the electrical contact element, and wherein the sidewall of the proximal portion of the electrode contacts the inner sidewall of the cavity of the electrical contact element during the sliding motion.

[0012] Preferably, the outer wall of the proximal portion of the electrode has a shape complementary to the inner wall of the cavity of the electrical contact element. Preferably, the outer wall of the proximal portion of the electrode and the inner wall of the cavity of the electrical contact element are cylindrical, wherein the gap between the sidewall of the proximal portion of the electrode and the inner wall of the cavity of the electrical contact element is 0.02 mm to 0.1 mm.

[0013] Preferably, the spring is a coiled compression spring. The spring may be made of a conductive material, such as metal, or of a non-conductive material.

[0014] Preferably, the cavity within the electrical contact element has a cylindrical shape.

[0015] Preferably, the electrical contact element has a tubular portion including the cavity, wherein an insulating element forms a sleeve on the tubular portion of the electrical contact element, and preferably, the electrical contact element surrounds the outer wall of the cavity of the electrical contact element.

[0016] Preferably, the insulating element has at least one support protrusion at its proximal end, the support protrusion including a support surface for the proximal end of the spring.

[0017] According to a particularly preferred embodiment, the insulating element has a stop portion on its outer side, the stop portion being used to fix the proximal end of the spring between the stop portion and the supporting surface of the insulating element. The stop portion may be formed by an annular protrusion or a set of protrusions on the outer surface of the insulating element.

[0018] Preferably, the electrical contact element is provided with a support flange, and the insulating element abuts against the support flange. In an embodiment, it is also feasible for the electrical contact element to be tubular without a support flange, wherein the proximal end of the insulating element will directly abut against the power supply component.

[0019] This component is used in plasma arc welding torches, and preferably also includes:

[0020] nozzle;

[0021] A retainer having a tubular shape; and

[0022] A vortex ring has a tubular shape and a supply opening in its sidewall, wherein the distal portion of the vortex ring is attached to a nozzle and the proximal portion of the vortex ring is attached to a retainer, wherein the nozzle, vortex ring and retainer are arranged coaxially and form a common cavity, wherein an electrode is slidably arranged in the common cavity along the common axis, wherein the electrode is provided with ribs on its outer side, the ribs extend helically and have gaps along the inner side of the vortex ring and / or retainer.

[0023] Preferably, the gap between the sidewall of the proximal portion of the electrode and the sidewall of the cavity of the electrical contact element is smaller than the gap between the electrode rib and the inner wall of the eddy ring and the retainer.

[0024] Preferably, the cavity of the electrical contact element, the insulating element disposed thereon, and the spring are arranged coaxially with each other, and most preferably coaxially with the welding torch. Preferably, the spring extends along the outer side wall of the insulating element, and the insulating element extends along the outer side wall of the electrical contact element.

[0025] The aforementioned defects in the prior art are also eliminated by a plasma arc welding torch operation method, which includes the following steps:

[0026] a) The electrode is slidably disposed in the cavity of the plasma arc welding torch along its axial direction, wherein the electrode is spring-biased to a forward position in which the distal end of the electrode contacts the nozzle.

[0027] b) Current is applied to the power supply component, and the current is further conducted to the electrodes via electrical contact elements;

[0028] c) Then, gas is introduced into the cavity of the plasma arc welding torch, which overcomes the force of the spring to push the electrode to its rear position, thereby establishing a guiding arc between the electrode and the nozzle.

[0029] d) Then, the electric arc is transferred to the workpiece being processed.

[0030] In step a), an insulating element is arranged on the electrical contact element to prevent current from being transmitted from the electrical contact element to the electrode via the spring, wherein the electrode is arranged such that its proximal portion extends into the cavity of the electrical contact element.

[0031] In steps b) and c), current flows from the electrical contact element through the contact between the inner wall of the cavity of the electrical contact element and the outer wall of the proximal portion of the electrode, at least until it reaches the rear position of the electrode.

[0032] As used herein, the proximal representation presents the portion or surface closer to the power source when considering the current path (i.e., further away from the workpiece to be processed), and the distal representation presents the portion or surface closer to the workpiece to be processed when considering the current path (i.e., further away from the power source). Attached Figure Description

[0033] Exemplary embodiments of the invention are described in the accompanying drawings, in which:

[0034] Figure 1 A longitudinal sectional view of a first exemplary embodiment of an assembly for contact-activated plasma arc welding torch is shown, the assembly including an electrode, a nozzle, and a vortex ring;

[0035] Figure 2 A longitudinal sectional view of a second exemplary embodiment of the component is shown, with the electrodes in the front position;

[0036] Figure 3 A longitudinal sectional view of a second exemplary embodiment of the component is shown, with the electrodes in a rear position; and

[0037] Figure 4 It is shown in the form of an exploded diagram. Figure 2 and Figure 3 Components. Detailed Implementation

[0038] Figure 1 The assembly shown for contact-starting a plasma arc welding torch includes a nozzle 2, the distal end of which includes a through-outlet opening 50 for discharging the plasma arc and plasma gas. The distal end of a vortex ring 10 is connected to the proximal end of the nozzle 2, and the proximal end of the vortex ring 10 is connected to a retainer 1, which is attached via its proximal end to a power supply component 8 for supplying electrical power.

[0039] Nozzle 2, vortex ring 10 and retainer 1 form a common cavity, in which electrode 3 is slidably arranged along the common longitudinal axis 26 of nozzle 2, vortex ring 10, retainer 1 and electrode 3.

[0040] The retainer 1 and the vortex ring 10 have a tubular shape, wherein the wall of the vortex ring 10 includes a supply opening 23 for plasma gas to enter the common cavity.

[0041] The retainer 1 is made of insulating material, and its distal end is adapted to be connected to the eddy ring 10.

[0042] Electrode 3 includes a distal end portion, a middle portion, and a proximal end portion 14. The distal end portion includes an emitting element 19, for example, made of hafnium. The middle portion of electrode 3 is provided with an outer rib 9, which extends spirally along the outer side wall of the electrode. The outer peripheral wall of the rib 9 abuts against the inner peripheral wall of the vortex ring 10 and ultimately has a gap with the inner peripheral wall of the retainer 1, thereby defining the movement of electrode 3 along its longitudinal axis 26.

[0043] An electrical contact element 6 is provided in the retainer 1, wherein the proximal contact surface 25 of the electrical contact element is adapted to abut against the distal contact surface 20 of the power supply component 8. Additionally, the electrical contact element 6 includes a cavity located on the opposite side of the proximal contact surface 25, into which a proximal end portion 14 of an electrode can be inserted, the outer wall of the proximal end portion 14 of the electrode contacting the inner wall of the cavity of the electrical contact element 6. More specifically, the outer wall of the proximal end portion 14 of the electrode 3 is complementary in shape to the inner wall of the cavity of the electrical contact element, i.e., having a gap in the range of 0.02 mm to 0.1 mm. Preferably, the outer wall of the proximal end portion 14 of the electrode and the inner wall of the cavity of the electrical contact element 6 are tubular or cylindrical, but they may also have other cross-sectional shapes, as long as they are in surface contact and allow movement relative to each other along axis 26.

[0044] The gap between the outer wall of the proximal end portion 14 of electrode 3 and the inner wall of the cavity of electrical contact element 6 is smaller than the gap between the outer peripheral wall of rib 9 of electrode 3 and the inner wall of eddy ring 10 or retainer 1.

[0045] Even in the front position of electrode 3, the proximal end portion 14 extends at least partially into the cavity of electrical contact element 6, wherein in the front position, the distal end of electrode 3 contacts nozzle 2.

[0046] The electrical contact element 6 is made of conductive material, and an insulating element 5 is disposed on the electrical contact element 6, the insulating element 5 having a support surface 51 for supporting the proximal end of the spring 4.

[0047] Additionally, the electrical contact element 6 includes a support flange 29. The support flange 29 includes a through opening 15, with its inlet located on the distal surface of the support flange 29, i.e., the side facing the spring 4 and the insulating element 5, and its outlet located on the proximal surface of the support flange 29, i.e., the side facing away from the spring 4 and the insulating element 5. These outlets of the through opening 15 are interconnected via a distribution groove 17 in the proximal contact surface 25 of the electrical contact element 6. The distribution groove 17 may, for example, be annular.

[0048] Electrode 3 has a support surface 31 facing the support surface 51 of insulating element 5, wherein the support surfaces 31 and 51 are arranged at intervals. A spring 4 is provided between the support surface 31 of electrode 3 and the support surface 51 of insulating element 5. The spring 4 is used to push electrode 3 in a direction away from power supply component 8 to the outlet opening of nozzle 2, thereby pushing electrode 3 in a distal direction.

[0049] In the illustrated embodiment, the insulating element 5 is tubular and has a support protrusion 24 in the form of a flange or collar at its proximal end. This support protrusion 24 rests its proximal surface on the support flange 29 of the electrical contact element 6, and its distal surface forms the support surface 51 of the insulating element 5. In the illustrated embodiment, the support protrusion 24 has slits 52 for allowing plasma gas to pass through, wherein these slits 52 are at least partially aligned with the through opening 15 in the electrical contact element 6. According to alternative embodiments, multiple support protrusions 24 are present. The tubular wall of the insulating element 5 extends along the outer side of the cavity wall of the electrical contact element 6, thereby preventing conductive contact between the spring 4 and the outer wall of the cavity of the electrical contact element 6.

[0050] Additionally, the insulating element 5 has a stop portion 30 in the form of annular ribs, which is used to attach the spring 4 to the insulating element 5 by positioning the proximal portion of the spring 4 between the stop portion 30 and the support protrusion 24. The stop portion 30 on the insulating element 5 may also be in the form of a set of protrusions or the like.

[0051] The angle between the side surface of the stop portion 30 and the side surface of the insulating element 5 is greater on the side facing the support surface 51 of the insulating element 5 than on the side away from the support surface 51 of the insulating element 5. This facilitates the mounting or attachment of the spring 4 to the insulating element 5 while reducing the risk of the spring 4 slipping off the insulating element 5 during assembly or disassembly of the assembly.

[0052] Figure 1 The component operates as follows: Due to the action of spring 4, electrode 3 is positioned at the front, so that its distal end contacts nozzle 2. Current is applied to power supply component 8 to initiate the arc ignition mode. Current flows from power supply component 8 through the proximal contact surface 25 of electrical contact element 6 to electrical contact element 6, and from electrical contact element 6 through the inner wall of the cavity of electrical contact element 6 and the sidewall of the proximal end portion 14 of electrode 3 to electrode 3.

[0053] Gas is introduced into the nozzle 2 and the cavity within the vortex ring 10 through the inlet opening 23, thereby increasing the pressure in the cavity and causing the electrode 3 to move from a front position to a rear position. During this movement, the distal end portion of the electrode 3 moves away from the nozzle 2, and current continues to flow from the electrical contact element 6 to the electrode 3 through the inner wall of the electrical contact element 6 and the sidewall of the proximal end portion 14 of the electrode 3. Simultaneously, a guiding arc is generated between the nozzle 2 and the electrode 3.

[0054] After reaching the rear position of electrode 3, the proximal contact surface 28 of the proximal end portion 14 abuts against the distal contact surface 27 of the electrical contact element 6, which faces the proximal contact surface 28. Subsequently, the electric arc can be transferred from electrode 3 to the material being processed, thus switching the welding torch to the arc transfer mode, i.e., the working mode.

[0055] In addition, part of the gas introduced into the cavity in which the electrodes 3 are arranged is carried away from the assembly through the opening 50 in the nozzle 2, and another part is carried away through the cut 52 in the insulating element 5, the through opening 15 in the electrical contact element 6 and the outlet opening 16 in the power supply component 8.

[0056] Gases such as air, N2, Ar, or mixtures of N2 and H2 can be used.

[0057] Spring 4 is always insulated from electrical contact element 6 by insulating element 5, and no current flows through spring 4 in any mode.

[0058] Figures 2 to 4 The second embodiment shown also includes a holder 1 having a tubular shape, which is attached by its proximal end to the distal end of a power supply component 8 for supplying electrical power, for example using a conventional type of attachment for a plasma arc welding torch.

[0059] The distal end of the power supply component 8 includes a distal contact surface 20, which is used to contact the electrical contact element 6 and the proximal contact surface 28 of the electrode 3.

[0060] Electrical contact element 6 is made of conductive material, and... Figures 2 to 4 The illustrated embodiment includes a through cavity into which the proximal end portion 14 of the electrode 3 is inserted. Therefore, Figures 2 to 4 The implementation methods shown are the same as Figure 1 The difference in the embodiment shown is that the cavity in the electrical contact element 6 is a through channel, which means that at the position where the end 14 of the electrode 3 is inserted into the cavity of the electrical contact element 6 to the maximum extent, and thus at the rear position of the electrode 3, the proximal contact surface 28 of the proximal end portion 14 of the electrode 3 abuts against the distal contact surface 20 of the power supply component 8 (and the current transfer from the power supply component 8 to the electrode 3 mainly occurs directly, i.e., through the contact between the distal contact surface 20 of the power supply component and the proximal contact surface 28 of the electrode 3).

[0061] In the forward position of electrode 3, i.e., the front position, the proximal contact surface 28 of electrode 3 is spaced apart from the distal contact surface 20 of power supply component 8, and the distal contact surface of electrode 3 is in contact with the inner surface of nozzle 2.

[0062] and Figure 1 The implementation method is similar. Figures 2 to 4 The embodiment also includes a gap between the inner wall of the cavity of the electrical contact element 6 and the sidewall of the proximal end portion 14 of the electrode 3, in the range of 0.02 mm to 0.1 mm.

[0063] This gap ensures that electrode 3 can be moved from the front position to the rear position, or more precisely, ensures that the proximal end portion 14 of electrode 3 can move within the cavity of electrical contact element 6, and that when electrode 3 is in the front position and when electrode 3 moves between the front and rear positions, the proximal end portion 14 contacts the sidewall of electrical contact element 6 to transfer current.

[0064] Additionally, it is possible to Figures 1 to 3 The path of the gas seen in the image begins from the cavity of nozzle 2, that is, along the spiral rib 9 at electrode 3, passes through the cut in the support protrusion 24 of insulating element 5, passes through the through opening 15 in the support flange 29 of electrical contact element 6, and passes through the outlet opening 16 in power supply component 8.

[0065] For example, when the support protrusion 24 has a sufficiently small cross-section to allow gas to enter the through opening 15 in the electrical contact element 6, the cut in the support protrusion 24 of the insulating element 5 can be omitted, or, instead of the support protrusion 24, a set of radial protrusions can be formed to support the spring.

[0066] The insulating element 5 is preferably made of a material that provides electrical insulation and good heat resistance, such as heat-resistant plastic, and most preferably resistant to temperatures up to at least 150°C.

[0067] In another embodiment, not shown, the insulating element 5 may be in the form of an insulating coating, or ultimately in the form of an insulating layer on a portion of the outer surface of the electrical contact element 6, particularly on the supporting surface of the electrical contact element 6 and on the outer sidewalls of the inner cavity of the electrical contact element 6. In this case, the insulating element 5 may be made of a suitable plastic material that provides electrical insulation and good thermal resistance.

[0068] Although various embodiments have been described, it will be apparent to those skilled in the art that other possible alternatives to the embodiments can be readily found. Therefore, the scope of the invention is not limited to these exemplary embodiments, but is defined by the appended claims.

Claims

1. An assembly for a plasma arc welding torch, comprising: The electrical contact element (6) has a proximal contact surface (25) and a cavity, the proximal contact surface (25) being used to contact the power supply component (8), and the cavity having an inner sidewall for contacting the sidewall of the proximal end portion (14) of the electrode (3); as well as A spring (4) is used to push the electrode (3) away from the electrical contact element (6). The component is characterized in that it further includes: An insulating element (5) is arranged on the electrical contact element (6) and is adapted to prevent current from being transmitted from the electrical contact element (6) to the spring (4).

2. The component according to claim 1, characterized in that, The assembly further includes an electrode (3), wherein a proximal end portion (14) of the electrode is insertable into the cavity of the electrical contact element (6), wherein the sidewall of the proximal end portion (14) of the electrode (3) contacts the inner sidewall of the cavity of the electrical contact element (6).

3. The component according to claim 2, characterized in that, The sidewall of the proximal end portion (14) of the electrode (3) has a shape complementary to the inner sidewall of the cavity of the electrical contact element (6), wherein the gap between the sidewall of the proximal end portion (14) of the electrode (3) and the inner sidewall of the cavity of the electrical contact element (6) is 0.02 mm to 0.1 mm.

4. The component according to any one of claims 1 to 3, characterized in that, The electrical contact element (6) has a tubular portion including the cavity, wherein the insulating element (5) forms a sleeve on the tubular portion of the electrical contact element (6).

5. The component according to any one of claims 1 to 3, characterized in that, The insulating element (5) has at least one support protrusion (24) at its proximal end, the support protrusion (24) including a support surface (51) for supporting the proximal end of the spring (4).

6. The component according to claim 5, characterized in that, The insulating element (5) has a stop (30) on its outer side, the stop (30) being used to fix the proximal end of the spring (4) between the stop (30) and the support surface (51) of the insulating element (5).

7. The component according to claim 4, characterized in that, The electrical contact element (6) is provided with a support flange (29), and the insulating element (5) abuts against the support flange (29).

8. The component according to claim 3, characterized in that, The component also includes: Nozzle (2); The retainer (1) has a tubular shape; and A vortex ring (10) has a tubular shape and a feed opening (23) in its sidewall, wherein the distal portion of the vortex ring (10) is attached to the nozzle (2) and the proximal portion of the vortex ring (10) is attached to the retainer (1), wherein the nozzle (2), the vortex ring (10) and the retainer (1) are arranged coaxially and form a common cavity, wherein the electrode (3) is slidably arranged in the common cavity along a common axis (26), wherein the electrode (3) is provided with ribs (9) on its outer side, the ribs (9) extending helically and having gaps along the inner side of the vortex ring (10) and / or the retainer (1).

9. The component according to claim 8, characterized in that, The gap between the sidewall of the proximal end portion (14) of the electrode (3) and the sidewall of the cavity of the electrical contact element (6) is smaller than the gap between the rib (9) of the electrode (3) and the inner wall of the eddy ring (10) and the retainer (1).

10. A method for operating a plasma arc welding torch, comprising the following steps: a) The electrode (3) is slidably arranged in the cavity of the plasma arc welding torch along its axial direction, wherein the electrode is biased to a front position by a spring (4), in which the distal end of the electrode contacts the nozzle (2). b) Apply current to the power supply component (8), and the current is also conducted to the electrode (3) via the electrical contact element (6). c) Then, gas is introduced into the cavity of the plasma arc welding torch, and the gas pushes the electrode (3) to its rear position against the force of the spring (4), wherein a guiding arc is established between the electrode (3) and the nozzle (2); d) Then, the electric arc is transferred to the workpiece to be processed; The feature is that, in step a), an insulating element (5) is arranged on the electrical contact element (6) to prevent current from flowing from the electrical contact element (6) to the electrode (3) via the spring (4), wherein the electrode (3) is arranged such that its proximal end portion (14) extends into the cavity of the electrical contact element (6), and In steps b) and c), the current is transmitted from the electrical contact element (6) through the contact between the inner wall of the cavity of the electrical contact element (6) and the outer wall of the proximal end portion (14) of the electrode (3), at least until reaching the rear position of the electrode (3).

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