Brazed electrode for plasma cutting torch

Abstract

The present application relates to brazed electrodes for plasma cutting torches. A silver-copper cutting electrode assembly and method of making the same are specifically disclosed having optimized attributes that allow for improved durability, integrity, and manufacturability. The electrode has a silver tip portion brazed to a copper body portion, with the silver portion and the joint having specific structural relationships.

Description

Background of the Invention This application is a divisional application of the application filed on February 24, 2018, with application number 201810156406.7 and invention title "Brazing Electrode for Plasma Cutting Torch". Technical Field

[0002] The systems and methods of the present invention relate to plasma cutting, and more specifically to a brazing electrode for arc plasma cutting. Background Technology

[0003] The use of plasma cutting systems has been developed across various industries, leading to a growing need for increased durability and lifespan of the torch and its components. This is particularly true for internal torch parts such as electrodes. As is generally known, plasma cutting involves the use of high-current plasma jets that generate significant heat during the cutting process and can produce spatter during piercing or arc initiation. This high heat and spatter adversely affect the service life of torch components, necessitating replacement and resulting in downtime. Therefore, improvements are needed to reduce this downtime and increase the service life of torch components.

[0004] By comparing conventional, traditional, and proposed methods with the embodiments of the invention illustrated in the remainder of this application with reference to the accompanying drawings, the further limitations and disadvantages of these methods will become apparent to those skilled in the art. Summary of the Invention

[0005] Embodiments of the present invention include a brazing electrode and a method for manufacturing a brazing electrode having a silver tip portion and a copper body, wherein the silver portion is brazed to the copper body. The use of silver improves the heat dissipation characteristics of the electrode, and brazing allows for easier fabrication of composite electrodes with optimal heat dissipation characteristics.

[0006] This application provides the following: 1) A composite plasma cutting electrode, comprising: a body portion made of a first material, the body portion having a wall portion defining a cavity and a distal end, the distal end having a distal end face and a first shoulder engagement portion extending upstream from the distal end face, wherein the shoulder portion includes a first surface and a second surface; and an end portion made of a second material, the end portion having a distal end face, an end cavity located in the distal end face, an upstream end face, and a second shoulder engagement portion, wherein an emission insert is disposed in the end cavity, the second shoulder engagement portion extending downstream from the upstream end face and having a first surface and a second surface, wherein the end portion The upstream end face of the first shoulder joint portion makes physical contact with the first surface of the first shoulder joint portion; wherein the second surface of the first shoulder joint portion is adjacent to the second surface of the second shoulder portion, such that a first gap exists between the respective second surfaces; wherein the first surface of the second shoulder joint portion is adjacent to the distal end face of the body portion, such that a second gap exists between the first surface of the second shoulder joint portion and the distal end face of the body portion; and wherein the first gap and the second gap are each filled with brazing material, the brazing material thereby connecting the body portion to the end portion.

[0007] 2). The electrode as described in 1), wherein the second gap is larger than the first gap.

[0008] 3) The electrode as described in 1), wherein the first gap is in the range of 0.001 inches to 0.006 inches.

[0009] 4). The electrode as described in 1), wherein the second void is in the range of 0.002 to 0.0035.

[0010] 5) The electrode as described in 1), wherein the wall portion has a first thickness upstream of the first shoulder joint portion and a second thickness downstream of the second surface of the first shoulder joint portion, wherein the second thickness is in the range of 35% to 65% of the first thickness.

[0011] 6) The electrode as described in 1), wherein the wall portion has a first thickness upstream of the first shoulder joint portion and a second thickness downstream of the second surface of the first shoulder joint portion, wherein the second thickness is in the range of 40% to 55% of the first thickness.

[0012] 7). The electrode as described in 1), wherein the first material is copper, the second material is silver, and the brazing material contains silver.

[0013] 8). The electrode as described in 1), wherein the electrode assembly has a total length L and the end portion has a length SL, wherein SL is in the range of 10% to 20% of L.

[0014] 9). The electrode as described in 1), wherein the electrode assembly has a total length L and the end portion has a length SL, wherein SL is in the range of 12% to 17% of L.

[0015] 10). A method for manufacturing a composite electrode, comprising: providing a body portion made of a first material, the body portion having a wall portion defining a cavity and a distal end, the distal end having a distal end face and a first shoulder engagement portion extending upstream from the distal end face, wherein the shoulder portion includes a first surface and a second surface; providing an end portion made of a second material, the end portion having a distal end face, an end cavity located in the distal end face, an upstream end face, and a second shoulder engagement portion, wherein an emission insert is disposed in the end cavity, the second shoulder engagement portion extending downstream from the upstream end face and having a first surface and a second surface; inserting the end portion into the distal end of the body portion such that the end... The upstream end face of the head portion makes physical contact with the first surface of the first shoulder joint portion, wherein the second surface of the first shoulder joint portion is adjacent to the second surface of the second shoulder portion such that a first gap exists between the respective second surfaces, and wherein the first surface of the second shoulder joint portion is adjacent to the distal end face of the body portion such that a second gap exists between the first surface of the second shoulder joint portion and the distal end face of the body portion; and the end portion is brazed to the body portion using brazing material to connect the body portion and the end portion, wherein the first gap and the second gap are each filled with the brazing material.

[0016] 11). The method as described in 10), wherein the second gap is larger than the first gap.

[0017] 12). The method as described in 10), wherein the first gap is in the range of 0.001 inches to 0.006 inches.

[0018] 13). The method as described in 10), wherein the second gap is in the range of 0.002 to 0.0035.

[0019] 14). The method as described in 10), wherein the wall portion has a first thickness upstream of the first shoulder joint portion and a second thickness downstream of the second surface of the first shoulder joint portion, wherein the second thickness is in the range of 35% to 65% of the first thickness.

[0020] 15). The method as described in 10), wherein the wall portion has a first thickness upstream of the first shoulder joint portion and a second thickness downstream of the second surface of the first shoulder joint portion, wherein the second thickness is in the range of 40% to 55% of the first thickness.

[0021] 16). The method as described in 10), wherein the first material is copper, the second material is silver, and the brazing material contains silver.

[0022] 17). The method as described in 10), wherein the electrode assembly has a total length L and the end portion has a length SL, wherein SL is in the range of 10% to 20% of L.

[0023] 18). The method as described in 10), wherein the electrode assembly has a total length L and the end portion has a length SL, wherein SL is in the range of 12% to 17% of L. Attached Figure Description

[0024] The above and / or other aspects of the invention will become more apparent from the accompanying drawings, which describe exemplary embodiments of the invention in detail with reference to the drawings, in which: Figure 1 This is an illustrated representation of an exemplary embodiment of the torch head assembly that can utilize the electrodes described herein; Figure 2A This is an illustrated representation of the initial manufacturing stage of the exemplary electrodes and exemplary nozzles described herein. Figure 2B This is an illustrated representation of an exemplary embodiment of the finished electrode as described herein; Figure 3A yes Figure 2A A graphical representation of the cross-section of the electrode in the initial stage; Figure 3B yes Figure 2B The diagram shows a cross-section of the finished electrode; and Figure 4 This is a schematic representation of a cross-section of the exemplary electrode described herein. Detailed Implementation

[0025] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. The described exemplary embodiments are intended to aid in understanding the invention and are not intended to limit the scope of the invention in any way. Throughout the text, similar reference numerals denote similar elements.

[0026] It should be noted that, for the purposes of the discussion below, the electrode embodiments discussed herein will be described as liquid-cooled electrodes that can be used in mechanized plasma arc cutting systems. However, the exemplary embodiments are not limited to use in such arc cutting systems, and the embodiments can be used in handheld cutting systems as well as air-cooled systems. Therefore, the following discussion is intended to be exemplary and informative. Further, the following discussion will use terms such as “distal” and “downstream.” In the context of this application, it should be understood that these terms refer to the end closer to the emitting plasma of the torch. For example, the distal end of the torch is the end of the torch's emitting plasma jet that performs the cut. Further, if something is “downstream” of another component, it is closer to the distal end of the torch. Similarly, using the term “upstream” will generally indicate that something is further away from the distal end of the torch.

[0027] Since the manufacture, assembly and use of electric arc cutting torches are generally known to those skilled in the art, the details of their components and parts will not be described here.

[0028] Turn now Figure 1 , Figure 1 A cross-section of an exemplary torch head 301 that can be used in embodiments of the present invention is depicted. As is generally known, the torch head 301 has a protective cap 303, which is held in place by an outer retaining cap 307. Inside the protective cap 303 is a nozzle 200, which is held in place by an inner retaining cap 409. Between the inner retaining cap 409 and the protective cap 303 is a protective gas vortex 407 that delivers and imparts flow to the protective gas, which is guided between the inner retaining cap 409 and the protective cap 303.

[0029] Upstream of nozzle 200 are electrode 500 and cooling pipe 401, both inserted together into the cavity of nozzle 200. The plasma arc is generated by electrode 500, and cooling pipe 401 guides cooling fluid to electrode 500 to maintain it at an acceptable operating temperature. Between electrode 500 and nozzle 200 is a plasma gas vortex ring 405, which imparts vortices to the plasma gas, helping to maintain a stable arc during cutting and cooling nozzle 200. Plasma gas vortex ring 405 has a distal surface 405' that seats on the inner seat surface 240 of nozzle 200.

[0030] Embodiments of the present invention relate to an electrode 500, which will be described in more detail below.

[0031] It is generally known that using silver in plasma cutting electrodes can increase their cutting life. However, due to the cost of silver, electrodes using silver are often much shorter than those using copper electrodes. Therefore, users of these electrodes must carry two different torch assemblies to accommodate both silver and copper electrodes. Embodiments of the present invention avoid the need to accommodate two different electrode lengths by utilizing a composite silver-copper electrode that achieves the benefits of using silver without the cost and size adjustments required with silver electrodes.

[0032] However, the use of composite electrodes is also known, and these electrodes are manufactured using very complex processes (such as thermal bonding or friction welding). These processes are expensive and difficult to manufacture properly. Embodiments of the present invention alleviate these problems.

[0033] Turn now Figure 2A An exemplary electrode 500' in an unfinished state is shown. That is, an electrode 500' is shown prior to the brazing and final machining processes explained further below. In an exemplary embodiment of the invention, electrode 500' includes a copper body portion 503' and a silver distal portion 501' (or end portion), wherein the copper body portion has a cavity 507' that is open at both the upstream and distal ends of the body portion 503', such that the surface of the silver portion 501' intersects with the cavity 507', as shown. The body portion has walls defining the cavity portion. This allows for additional cooling of the silver portion 501' during operation. The distal end of the copper portion 503' has a shoulder portion 513 into which the silver portion 501' is inserted. That is, the diameter of the shoulder portion 513 in the body 503' is larger than the diameter of the cavity 507'. Furthermore, portion 501' has a cavity on its distal end face (its furthest surface), into which the hafnium insert 505' is to be inserted. Each of the shoulder 513 and the silver portion 501' is manufactured and configured such that the upstream surface 510 of the silver portion 501' rests against / contacts with the shoulder surface 511, as... Figure 2AAs shown. These components rest against each other such that there are no gaps between surfaces 510 / 511 when these components are assembled. However, when assembled together, a gap G exists between the shoulder portion 515 of the silver portion 501' and the shoulder portion 513 of the copper portion. (As seen, the shoulder portion 515 has a surface corresponding to the distal surface of the body 503 and a surface extending upstream from that surface to the uppermost end 511 of the end portion and corresponding to a similar surface on the shoulder portion 513 of the body portion 503). This gap G extends along both the horizontal and vertical adjacent surfaces of these shoulder portions. This gap G exists to allow for proper brazing of these components. That is, as shown, the wall surface extending toward the distal surface of the body portions 503' / 503 extends from the uppermost surface 510 of the body 503.

[0034] In other words, during the manufacturing process, as shown and described, each of the copper and silver portions is assembled to each other. The silver portion 501' is centered relative to the copper portion 503' as much as possible, so that the gap G around the shoulder portion is generally uniform / symmetrical. It should be noted that in some embodiments, the gap G distance in each of the horizontal and vertical planes may be the same. However, in other exemplary embodiments, the horizontal gap may be larger than, or in some embodiments smaller than, the vertical gap G. The gap geometry should be selected to maximize structural integrity and solder flow, as described below. Furthermore, as shown, the silver portion 501' may be chamfered at the outer edge of the gap G to influence the solder flow into the gap G.

[0035] Before inserting the hafnium insert 505' into the silver portion 501', the silver and copper components are brazed to each other. This can be done using silver brazing filler with a silver-based flux to ensure proper solder flow into the void G. Brazing can be performed using known methods, such as induction heating. The brazing operation should be completed such that the entire void G is filled with brazing filler and the contact surfaces 510 / 511 remain in contact with each other.

[0036] After the brazing operation is completed, the hafnium insert 505' can be inserted into the cavity in the silver portion 501'. By inserting it after brazing, there is no risk of damaging or breaking the hafnium during the brazing operation. Once brazing and assembly are complete, component 500 can be machined to its final dimensions, such as... Figure 2BAs shown, the outer surface of component 500 is machined to achieve the final external dimensions and shape of electrode 500. Additionally, cavity 507 is also machined to its final diameter, as shown. In some exemplary embodiments, cavity extension 517 (formed as an annulus) may be formed to increase the exposed surface area of ​​the silver portion 501 of electrode 500. When the final dimensions are achieved, component 500 provides an electrode with silver electrode performance at a significantly reduced cost and with a smaller copper electrode size.

[0037] Figure 3A yes Figure 2A An enlarged view of the components is shown. As shown, surfaces 510 / 511 are in contact with each other, while gaps G exist along both the vertical and horizontal portions, as illustrated in this figure. In this embodiment, the gap G along the horizontal portion is larger than the vertical gap. In some exemplary embodiments, the average gap G on the horizontal surface ranges from 0.01 inches to 0.006 inches. Additionally, in several exemplary embodiments, the vertical gap ranges from 0.02 inches to 0.0035 inches. In any case, the gap size should be selected to facilitate proper brazing of the components. It should be noted that although the surfaces of the shoulder portions of each of the end caps and the body are shown as horizontal and vertical and joined at right angles, several embodiments are not limited to this and the corners may be angled.

[0038] Figure 3B Depicting Figure 2B An enlarged view of the finished electrode 500 is shown. As shown, the distal end of the finished electrode 500 has a maximum outer diameter D (which may not necessarily be the maximum outer diameter of the electrode 500), and the copper portion has a wall thickness W (adjacent to the cavity 507). In several exemplary embodiments, the wall thickness W is in the range of 10% to 40% of the diameter D, and in other embodiments, the wall thickness W is in the range of 14% to 25% of the diameter D. Furthermore, the silver portion 501 has an insertion portion 520, as shown, which is a portion inserted into the copper portion 503. In some embodiments, the insertion portion 520 has a wall thickness SW less than the thickness W. In several exemplary embodiments, the wall thickness SW is in the range of 35% to 65% of the thickness W. Additionally, in several exemplary embodiments, the wall thickness of the insertion portion 520 is in the range of 40% to 55% of the thickness W. With these ratios, the thermal performance of the walls of the cavity 507 provides optimal thermal performance, structural integrity, and significantly improved manufacturing complexity and cost compared to known solutions.

[0039] Figure 4A cross-section of an exemplary electrode 500 is depicted. While the upstream end 530 is depicted as shown, several exemplary embodiments are not limited to this configuration, and other configurations may be used without departing from the spirit or scope of the invention. As shown, electrode 500 has a total length L that includes the distal end face of the silver portion 501 and the upstream end of the copper portion 503. The copper portion has a length SL extending from its distal end face to its upstream end face, which is the end face of the insertion portion 520. In an exemplary embodiment, the length SL is in the range of 10% to 20% of the total length L. In other exemplary embodiments, the length SL is in the range of 12% to 17% of the length L. These ratios allow the assembly to achieve the desired thermal performance and maximum structural integrity. For example, if the length of the silver portion 501 is too short, the brazing joint between the silver and copper will appear at a sufficient distance from the thermal gradient during the cutting operation, such that the brazing joint is not thermally encapsulated during operation. If these joints are too close together, the brazing joints may weaken and cause the assembly to fail. Furthermore, if the length is too long, the structural integrity of the component may be compromised, and the manufacturing and material costs will be higher. For example, a longer silver length may result in insufficient brazing penetration during assembly, leaving gaps that could lead to thermal stress concentration or otherwise adversely affect the thermal conductivity between components. Of course, minor deviations from the above ranges can be achieved according to the design configuration, but the aforementioned considerations must be taken into account to ensure proper continuous operation. In particular, the silver portion 501 should have a length sufficient to keep most or all of the brazed joint outside the higher temperature gradients and bands that will be achieved during continuous cutting. It is acceptable that some portions of the joint are within certain temperature gradient bands, but these portions should not be present in higher temperature gradient bands. Of course, this can also be affected by the brazing material used. In an exemplary embodiment of the invention, the maximum temperature experienced by the brazed joint during torch operation is less than 235°C, and the temperature difference across the joint (between adjacent materials) does not exceed 50°C. Therefore, the embodiments of the invention have a construction that optimizes electrode life and, under its construction, optimizes its thermal efficiency.

[0040] In view of the above, embodiments of the present invention provide high-performance cutting electrodes that are easy to manufacture and have significantly improved costs compared to known silver electrodes and silver composite electrodes.

[0041] Although the invention has been specifically shown and described with reference to exemplary embodiments thereof, the invention is not limited to these embodiments. It will be understood by those skilled in the art that many different changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined in the following claims.

Claims

1. A composite plasma cutting electrode, comprising: A body portion made of a first material, the body portion having a wall portion defining a cavity and a distal end, the distal end having a distal end face and a first shoulder engagement portion extending upstream from the distal end face, wherein the shoulder engagement portion includes a first surface and a second surface; as well as An end portion made of a second material, the end portion having a distal end face, an end cavity located in the distal end face, an upstream end face, and a second shoulder engagement portion, wherein a firing insert is disposed in the end cavity, and the second shoulder engagement portion extends downstream from the upstream end face and has a first surface and a second surface. The upstream end face of the end portion makes physical contact with the first surface of the first shoulder joint portion; The second surface of the first shoulder joint portion is adjacent to the second surface of the second shoulder portion, such that a first gap exists between the respective second surfaces. The first surface of the second shoulder joint portion is adjacent to the distal end surface of the body portion, such that a second gap exists between the first surface of the second shoulder joint portion and the distal end surface of the body portion. The first and second gaps are each filled with brazing material, which connects the body portion to the end portion. The second gap is larger than the first gap. The end portion includes an insertion portion, the wall portion has a first thickness and the insertion portion has a second thickness, the second thickness being in the range of 35% to 65% of the first thickness, and the distal end has a maximum outer diameter, the first thickness being in the range of 10% to 40% of the maximum outer diameter. The electrode has a total length L, and the end portion has a length SL, with SL ranging from 10% to 20% of L.

2. The electrode as claimed in claim 1, wherein, The first gap is in the range of 0.001 inches to 0.006 inches.

3. The electrode as claimed in claim 1, wherein, The second gap is in the range of 0.002 to 0.0035.

4. The electrode as claimed in claim 1, wherein, The second thickness is in the range of 40% to 55% of the first thickness.

5. The electrode as claimed in claim 1, wherein, The first material is copper, the second material is silver, and the brazing material contains silver.

6. The electrode as claimed in claim 1, wherein, SL is in the range of 12% to 17% of L.

7. A method for manufacturing a composite electrode, comprising: A body portion made of a first material is provided, the body portion having a wall portion defining a cavity and a distal end, the distal end having a distal end face and a first shoulder engagement portion extending upstream from the distal end face, wherein the shoulder engagement portion includes a first surface and a second surface; A tip portion made of a second material is provided, the tip portion having a distal end face, a tip cavity located in the distal end face, an upstream end face, and a second shoulder engagement portion, wherein a firing insert is disposed in the tip cavity, and the second shoulder engagement portion extends downstream from the upstream end face and has a first surface and a second surface. The end portion is inserted into the distal end of the body portion such that the upstream end face of the end portion makes physical contact with the first surface of the first shoulder joint portion, wherein the second surface of the first shoulder joint portion is adjacent to the second surface of the second shoulder portion such that a first gap exists between the respective second surfaces, and wherein the first surface of the second shoulder joint portion is adjacent to the distal end face of the body portion such that a second gap exists between the first surface of the second shoulder joint portion and the distal end face of the body portion. The end portion is brazed to the body portion using brazing material to connect the body portion and the end portion, wherein the first gap and the second gap are each filled with the brazing material; The second gap is larger than the first gap. The end portion includes an insertion portion, the wall portion has a first thickness and the insertion portion has a second thickness, the second thickness being in the range of 35% to 65% of the first thickness, and the distal end has a maximum outer diameter, the first thickness being in the range of 10% to 40% of the maximum outer diameter. The electrode has a total length L, and the end portion has a length SL, with SL ranging from 10% to 20% of L.

8. The method of claim 7, wherein, The first gap is in the range of 0.001 inches to 0.006 inches.

9. The method of claim 7, wherein, The second gap is in the range of 0.002 to 0.0035.

10. The method of claim 7, wherein, The second thickness is in the range of 40% to 55% of the first thickness.

11. The method of claim 7, wherein, The first material is copper, the second material is silver, and the brazing material contains silver.

12. The method of claim 7, wherein, SL is in the range of 12% to 17% of L.

13. A torch head, comprising: Protective cap, which is held in place by an external retaining cap; A nozzle, which is located inside the protective cap and held in place by an inner retaining cap; and A protective gas vortex is provided, which is located between the inner retaining cover and the protective cap.

14. The torch head as claimed in claim 13, further comprising: An electrode, located upstream of the nozzle; A cooling tube is located upstream of the nozzle, wherein the electrode and the cooling tube are inserted into the cavity of the nozzle; and A plasma gas vortex ring is located between the electrode and the nozzle, wherein the plasma gas vortex ring has a distal surface that is seated on the inner seat surface of the nozzle.

Images