Controlling and delivering gas in a plasma arc torch and related systems and methods

Abstract

In some aspects, a torch receiving device for coupling a plasma arc torch to a torch lead line may include a body having a first end connected to the torch lead line and a second end connected to the torch body; a set of ports within the first end fluidly connected to a set of fluid conduits within the torch lead; and a multi-way valve within the body and fluidly connected to the set of ports and to a torch gas conduit formed in the second end, the multi-way valve configured to: i) manipulate fluid flow between the first end and the second end to select from the primary gas entering the set of ports, ii) delivering the selected primary gas through the torch gas conduit to the torch body, and iii) fluidly connecting the torch gas conduit to a gas supply manifold of the plasma cutting system.

Description

[0001] Related applications This application is a continuation of U.S. Patent Application Serial No. 15 / 287,694, filed October 6, 2016, entitled “Controlling Plasma Arc Torches and Related Systems and Methods,” which claims the benefit of U.S. Provisional Patent Application Serial No. 62 / 237,780, filed October 6, 2015, entitled “Controlling Plasma Arc Torches and Related Systems and Methods,” the contents of both applications are hereby incorporated by reference in their entirety. This application also claims the benefit of U.S. Provisional Patent Application Serial No. 62 / 315,331, filed March 30, 2016, entitled “Gas Switching and Venting Proximate a PlasmaArc Torch,” the contents of which are hereby incorporated by reference in their entirety. Technical Field

[0002] This disclosure generally relates to plasma arc welding torch systems, and more specifically, to the control and delivery of gases to and within a plasma arc welding torch, as well as related systems and methods. Background Technology

[0003] Heat treatment torches (such as plasma arc welding torches) are widely used for heating, cutting, planing, and marking materials. A plasma arc welding torch generally includes an electrode, a nozzle with a central outlet orifice mounted within the torch body, electrical connections, a cooling passage, and a passage for the arc control fluid (e.g., plasma gas). A swivel ring is used to control the fluid flow pattern within the plasma chamber formed between the electrode and the nozzle. In some torches, a retaining cap may be used to hold the nozzle and / or swivel ring within the torch body. During operation, the plasma arc welding torch generates a plasma arc, which is a compressed jet of ionized gas with high temperature and sufficient momentum to facilitate the removal of molten metal. The power used to operate the plasma arc welding torch can be controlled by the power supply components of the plasma operating system. A power supply unit and / or metering console, typically positioned at a distance (e.g., several meters) relative to the welding torch, may include multiple electronic components configured to control and supply operating current to the plasma arc welding torch, provide gas flow to the plasma arc welding torch, and, in some cases, the movement of the plasma arc welding torch. This distance between the welding torch and the power supply unit / metering console may vary depending on the system and installation.

[0004] In plasma arc cutting systems, transient electrode life, cut quality and consistency, and overall operation can be influenced by or depend on the ramp time (e.g., the rate of rise and fall of plasma current and / or plasma gas during startup and shutdown), which can be selected during the development of process parameters for a given system. These process parameters (i.e., waveforms) are typically located in the power supply section (usually several meters from the actual torch tip) and are independent of the system configuration used. Some systems are configured to implement certain gas profiles and gas characteristics during transition, startup, or shutdown based on the desired characteristics of the arc during operation. For example, some systems can provide a desired combination of gas flow or current profiles for shutdown. Summary of the Invention

[0005] In some aspects, a torch receiving device for connecting a plasma arc welding torch to a torch lead of a plasma cutting system and for discharging the torch lead (and in some cases, the plasma arc welding torch) upstream through the plasma cutting system may include: a body having a first end fixedly connected to the torch lead and a second end fixedly connected to the torch body of the plasma arc welding torch; a set of ports disposed within the first end of the body and configured to be fluidly connected to a set of fluid conduits disposed within the torch lead; and a multi-way valve disposed within the body and fluidly connected to the set of ports and a torch gas conduit formed in the second end of the body, the multi-way valve being configured to: i) manipulate the fluid flow between the first and second ends of the body to select from primary gases entering the set of ports, ii) deliver the selected primary gas through the torch gas conduit to the torch body, and iii) fluidly connect the torch gas conduit to a gas supply manifold of the plasma cutting system to allow discharge of the torch gas conduit through the gas supply manifold.

[0006] An embodiment may include one or more of the following features.

[0007] The body may be formed of a substantially insulating material. The body may have a length of less than approximately 1 foot between the first end and the second end. The body may define a set of fluid flow paths substantially disposed within the body to fluidly connect a multi-port valve to a fluid conduit within the welding torch inlet.

[0008] The multi-port valve can be a three-way valve, fluidly connected to a first conduit of a group of fluid conduits, a second conduit of the group of fluid conduits, and a torch gas conduit, and configured to select a gas from the first or second conduit and allow the selected gas to be delivered to the torch body via the torch gas conduit. The multi-port valve can be positioned less than 12 inches from the plasma chamber of the plasma arc welding torch. The multi-port valve can be configured to switch the gas supply to the torch body via the torch gas conduit between the gases entering the group of ports.

[0009] The group of ports may include a first plasma gas port and a second plasma gas port, wherein the first plasma gas port is configured to receive a plasma preflow gas, and the second plasma gas port is configured to receive a plasma cutting flow gas. The group of ports may include a shielding gas port fluidly connected to a shielding gas conduit formed between a first end and a second end of the body. The torch gas conduit may have a volume of less than about 0.3 cubic inches. In some cases, the torch gas conduit has a volume of less than about 0.2 cubic inches. A torch lead may fluidly connect at least one of the group of conduits to atmospheric pressure for discharge. In some examples, a multi-port valve prevents excess plasma gas entering the torch gas conduit from being discharged upstream through the torch lead.

[0010] In some aspects, a plasma arc welding torch system for reverse-discharging plasma gas upstream via a plasma welding torch lead-in line may include: a plasma welding torch power supply unit having: a group of gas supply units including a first plasma gas and a second plasma gas; a torch lead-in manifold for fluidly connecting the group of gas supply units to the plasma welding torch lead-in line; and a discharge valve for discharging the first plasma gas to atmospheric pressure; a plasma welding torch lead-in line configured to be connected to the torch lead-in manifold, the plasma welding torch lead-in line defining a set of fluid passages for conveying the first plasma gas and the second plasma gas from the plasma welding torch power supply unit; and a welding torch receiving device for connecting the plasma arc welding torch to the plasma welding torch power supply unit, the welding torch receiving device having: a body having a first end connected to the plasma welding torch lead-in line and a second end fixedly connected to the welding torch body of the plasma arc welding torch; and a set of ports defined within the body. The body comprises a first end and a group of fluid passages fluidly connected to the plasma torch lead-in line; and a three-way multi-port valve disposed within the body and fluidly connected to the group port to fluidly connect to a first passage and a second passage of the group of fluid passages in the plasma torch lead-in line, and fluidly connected to a torch gas conduit formed in the second end of the body, the torch gas conduit having a volume of less than approximately 0.3 cubic inches, the three-way multi-port valve being configured to: i) manipulate the fluid flow between the first and second ends of the body to select from the primary gas entering the group port, ii) deliver the selected primary gas through the torch gas conduit from the first or second passage to the torch body, and iii) fluidly connect the torch gas conduit to the torch lead-in manifold of the plasma torch power supply unit to allow the torch gas conduit to discharge to atmospheric pressure through the torch lead-in manifold.

[0011] In some aspects, a method of operating a plasma cutting system, which involves selecting between a group of plasma gases in a torch receiving device of a torch lead connected to the plasma cutting system, the torch receiving device having a valve configured to manipulate the fluid flow of the plasma arc torch between the groups of plasma gases, may include: supplying pre-flow plasma gas through a first conduit connected to the torch lead of the torch receiving device, the pre-flow plasma gas traveling through the valve to the plasma arc torch; and, in the presence of pre-flow plasma... In the case of a plasma arc welding torch, the plasma arc is ignited; the cutting plasma gas is selected by activating a valve to: i) restrict the further downstream flow of the pre-flow plasma gas to the plasma arc welding torch, and ii) allow the cutting plasma gas to flow through the valve from the second conduit of the torch inlet to the plasma arc welding torch; the first conduit of the torch inlet is discharged to atmospheric pressure at a manifold upstream of the plasma arc welding torch to release the pre-flow plasma gas from the torch inlet; and the cutting plasma gas is used to perform the plasma cutting operation.

[0012] An embodiment may include one or more of the following features.

[0013] The method may further include activating a valve to: i) restrict further downstream flow of cutting plasma gas from the second conduit to the plasma arc welding torch, and ii) allow remaining cutting plasma gas to be discharged upstream through the torch inlet and from a manifold within the power supply section of the plasma cutting system, thereby reducing the pressure in the plasma arc welding torch. The method may further include initiating a plasma arc shutdown procedure.

[0014] Discharge from the first conduit of the welding torch lead may include opening a valve within the power supply section of the plasma cutting system to which the welding torch lead is attached. Selection of the cutting plasma gas allows for switching the gas supply at the plasma arc welding torch from the pre-flow plasma gas in the first conduit to the cutting plasma gas in the second conduit in less than approximately one second.

[0015] In some examples, the distance between the valve in the torch receiving device and the manifold in the power supply section of the plasma cutting system can be at least about 2 meters.

[0016] The embodiments described herein may have one or more of the following advantages.

[0017] The systems and components described herein can be used to perform any of a variety of methods for controlling and delivering gases within a plasma cutting system. For example, precise and dynamic control by the systems described herein can be used to control, modify, customize, manipulate, and optimize gas flow and / or selection within a plasma cutting system. In some embodiments, this can correspond to or match gas distribution, pressure, and selection for a given process to improve cutting quality or extend electrode life by reducing plasma torch ramp-down error. Ramp-down error (RDE) can occur when a plasma system experiences a sudden loss of the plasma arc, for example, when the plasma torch flows away from the workpiece and a coordinated ramp-down of the plasma gas chamber pressure and cutting current cannot be achieved (in some cases referred to as "long-life techniques"). A sudden loss of the arc without a proper arc-extinguishing procedure can cause high-pressure gas to blow over the molten emitter material and thus excessive wear. That is, a sudden loss of the arc can cause increased hafnium wear, especially in the presence of oxygen. For example, in some cases, without a proper arc extinguishing procedure, the high pressure of the continuing plasma gas flow (as if the plasma arc were still attached to the workpiece) can blow away molten emitter material when the plasma arc is abruptly lost, leading to wear. Therefore, precise and accurate plasma gas tilting techniques are particularly useful for extending electrode life when the steady-state cutting process transitions to torch shutdown (i.e., arc extinguishing). That is, when an undesirable arc loss is predicted / detected, failure to adjust the gas supply to address this impending loss can cause unnecessary electrode wear. The power supply can then take action to limit this unnecessary wear, thereby extending electrode life through rapid and responsive adjustment of the plasma gas supplied to the torch.

[0018] For example, the systems and methods described herein can be implemented and used in conjunction with other torch control systems that monitor these electrical parameters, system parameters, and control parameters to predict when the plasma arc will be lost, for example, when the plasma torch travels beyond the edge of the material being treated. In response, the power supply can act rapidly to prevent sudden arc loss, which can lead to electrode wear and reduced life. This rapid action to prevent sudden arc loss, as discussed below, may include adjusting the electrical parameters of the arc, the gas flow to the torch, or the movement of the torch itself. Additional details regarding ramp error detection and prevention can be found in the applicant's related co-pending U.S. Patent Application No. 15 / 287,694, filed October 6, 2016, entitled "Controlling Plasma Arc Torches and Related Systems and Methods," the entire contents of which are incorporated herein by reference in their entirety. This controlled gas delivery method during the shutdown process is illustrated to improve consumable life, such as the available electrode life. For example, electrode lifetime can be hampered (e.g., limited) by long plasma pressure descent times and transition times from pre-flow gas to cut flow gas.

[0019] However, the systems and methods described herein can be used to improve electrode life and torch performance by providing faster gas switching times. For example, conventional systems where the gas is switched at the power supply section can cause long gas switching times, resulting in some mixing of the pre-flow and cutting flow gases in the lead-in line delivered to the torch. This can cause problems because some gases have chemistry more suited to pre-flow, some to cutting, and some to ramping (e.g., during torch shutdown). Therefore, the ability to switch rapidly between these different gases in a controlled and precise manner can improve cut quality, consumable life, system responsiveness, and provide other benefits. However, using the systems described herein, the gas switching from pre-flow to cutting flow can occur at or near the torch, resulting in faster switching times and therefore longer electrode life. For example, some conventional systems may require at least 250 microseconds of ramping time, but some systems described herein can have ramping times of less than approximately 50 microseconds.

[0020] Furthermore, rapidly changing the gas supplied to the torch at a location near the torch (such as at the torch receiving device) can help to make torch performance and operation more stable across different torch configurations (e.g., torches of different lengths (e.g., different torch lead-in line lengths)). For example, some conventional systems have only one plasma gas line connected to the torch, which is used to supply both the pre-flow gas and the cutting flow gas. Therefore, the gas switching from the pre-flow to the cutting flow occurs away from the torch, and the actual gas conversion within the torch typically depends on (or is otherwise influenced by) the length of the gas lead-in line. However, the systems and methods described herein (where gas switching can occur much closer to the torch) provide torch control and gas switching response times that are substantially independent of lead-in length. For example, to discharge a desired gas (e.g., to discharge pre-flow gas for use with cutting flow gas, or to discharge cutting flow gas to extinguish the welding torch), conventional welding torch systems typically activate a valve (or have a vent valve) at or near the power supply (i.e., at the end of the lead line opposite the welding torch, in a gas metering control console, etc.) to change the gas supplied to the welding torch. Once the valve is activated, residual gas (e.g., gas present in the lead line) is typically allowed to escape through the welding torch from the valve. However, this can cause undesirable delays due to gas changes or undesirable gas mixing. Therefore, due to the systems and methods described herein, in which the multi-way valve is positioned close to the welding torch (e.g., less than about 12 inches), the gas can be switched from pre-flow gas to cutting flow gas much more quickly.

[0021] In addition to increasing the ability to switch gases for torch descent, the systems and methods described herein utilize rapid gas switching techniques during torch startup, for example, switching from pre-flow gas to cutting flow gas in a near-instantaneous (e.g., within less than approximately 50 microseconds) manner. As discussed in detail below, the pre-flow gases are more suitable for startup and extending electrode life, and are therefore intended for ignition. Gas switching can then occur once the arc has been transferred to provide a cutting flow gas more suitable for cutting. In some conventional systems, this switching occurs during arc transfer, but there is a considerable delay at the start of cutting to partially address this delay (e.g., the attenuation of the pre-flow gas from the lead-in line and its replacement by the cutting flow gas). However, using the systems and methods described herein with faster and better controlled gas switching, cutting can begin more rapidly and / or immediately / immediately after arc transfer.

[0022] Furthermore, the gas changeover procedure at or near the power supply unit in conventional systems can cause instability in the performance of torches with different lead / hose lengths. That is, conventional plasma cutting platforms offer varying lead / hose lengths (e.g., between the metering console (e.g., at the power supply unit) and the torch) to meet specific customer requirements. This length variation (which can range from approximately 6 feet to approximately 50 feet (or more)) can lead to unstable gas transition times and distributions, which compromises quality and stability, and / or causes variations in gas descent time, making consumable life partially dependent on system configuration and preventing customers from achieving consistent consumable performance. This means that the overall electrode life can be hampered by long plasma pressure descent times, which can be driven / required by the distance between control elements (e.g., gas control valves) and the torch. Additionally, electrode life is also affected by the transition from pre-flow gas to cutting flow gas, and the timing of this transition needs to be controlled. For example, in some conventional plasma systems, unwanted gases from the lead tube are vented from the torch itself, and longer lead tube lengths typically require a longer time to extract all residual gases compared to shorter lead tube lengths. However, in some examples, instead of extinguishing the plasma arc and then venting the gas from the lead tube line, the system described herein can be used to vent the gas supply line while the arc is still on. For example, instability can be reduced by adding a gas switching valve (e.g., a three-way valve) directly upstream of the torch and connecting two plasma lines (pre-flow and cut flow) to this valve. Thus, gas switching and predictable slop can be achieved regardless of lead tube length. Positioning the two plasma lines close to the torch helps provide rapid (e.g., near-instantaneous) gas switching (pre-flow to cut flow) and improved slop response. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a plasma arc welding torch system, which has a system for reverse-upward discharge of plasma welding torch lead lines through the plasma welding torch in the plasma arc welding torch.

[0024] Figure 2 This is a schematic diagram of a plasma arc welding torch system, which has a system for reverse discharge upstream through a valve located at or near the torch.

[0025] Figure 3 This is a side sectional view of an exemplary welding torch, which has a multi-way valve disposed therein for selectively supplying gas to a compartment area. Detailed Implementation

[0026] In some aspects, as discussed herein, the systems and methods described herein may include plasma cutting systems having one or more precisely and dynamically monitored and controlled gas parameters, such as plasma gas flow or shielding gas flow. Precise control of these systems has been found useful for implementing several advantageous torch control methods described herein. Exemplary methods (as discussed in detail herein) involve rapidly adjusting the flow of different plasma gases supplied to the torch during plasma arc initiation or descent procedures. More responsive gas handling has been found to produce better and / or more stable consumable performance and lifespan.

[0027] Reference Figure 1 In some cases, a plasma cutting system (e.g., a plasma arc welding torch system) 50 used for reverse-upward emission of plasma gas from a plasma arc welding torch through a plasma torch lead-in line may include a plasma torch power supply unit 100, a plasma torch lead-in line 120, a torch receiving device 140, and a plasma arc welding torch 150 having a torch body 160. The torch receiving device 140 may serve as an interface connection member between the lead-in line 120 and the plasma arc welding torch 150.

[0028] The power supply unit 100 may include a metering control console with a set of gas supplies, which may include a protective gas supply unit 102, a first processing gas (e.g., plasma gas (e.g., pre-flow plasma gas)) supply unit 104, and a second processing gas (e.g., plasma gas (e.g., cut-flow plasma gas)) supply unit 106. The configuration of the different gas supplies may vary based on the desired material handling operation. For example, in some cases, the first plasma gas 104 may include nitrogen. In some cases, the second plasma gas 106 may be oxygen. The gas supply unit may include various hardware components, such as valves (e.g., three-way valves or proportional valves) and pressure sensors, which can be used to control and monitor the gas flow.

[0029] The power supply unit 100 also typically includes a welding torch lead manifold 108. The welding torch lead manifold 108 can be used, for example, to selectively fluidly connect a group of gas supply units to the welding torch body 160 via a plasma welding torch lead line 120. The welding torch lead manifold 108 may include pneumatic switches that can open and close different flow paths to allow or restrict gas flow to and from the welding torch lead line 120.

[0030] The power supply unit 100 may also include a discharge unit (e.g., a discharge valve) 110 to reduce the pressure of one or more gases. For example, the discharge unit 110 may allow the gas to pass to atmospheric pressure. In some cases, the discharge valve 110 may be fluidly connected to the first processing gas supply unit 104 and configured to discharge the first processing gas (e.g., from the welding torch lead line, as discussed below) to the atmosphere. In some cases, as detailed below, this discharge may be performed to rapidly extract the processing gas (e.g., upstream) from the lead line 120 while the welding torch 150 (e.g., a chamber) is vented downstream / forward through the torch tip.

[0031] Plasma welding torch lead line 120 is configured to connect plasma welding torch 150 to power supply unit 102. For example, lead line 120 may be configured to connect to power supply unit 102 to link to torch lead manifold 108 and torch receiving device 140. Torch lead manifold 108 may be positioned outside / separated from power supply unit 102, or within power supply unit 102. Plasma welding torch lead line 120 is typically configured to deliver fluid (e.g., torch gas) to torch 150. For example, lead line 120 may define a set of fluid passages (e.g., conduits) to deliver a first plasma gas and a second plasma gas from plasma welding torch power supply unit to torch body 160. Lead line 120 may include shielding gas passage 122, a first processing gas passage 124, and a second processing gas passage 126. Shielding gas passage 122 delivers shielding gas to welding torch 150 (e.g., to welding torch receiving device 140). First processing gas passage 124 delivers first processing gas to welding torch 150 (e.g., to welding torch receiving device 140). Second processing gas passage 126 delivers second processing gas to welding torch 150 (e.g., to welding torch receiving device 140). The lead line may include any of a variety of structurally suitable components for delivering gases. For example, lead line 120 may include a multi-chamber hose, such as a hose having two or more (e.g., three, to accommodate shielding gas, first processing gas, and second processing gas) separate flow paths. In some cases, lead line 120 may include three different hoses connected to each other.

[0032] The plasma welding torch lead line 120 can have any of a variety of lengths, depending on the desired operating and usage environment. For example, in some cases, the plasma welding torch lead line 120 can have a length of 121, which is at least about 2 meters, 5 meters, or 50 meters.

[0033] The torch receiving device 140 may be configured, for example, to connect the plasma arc welding torch body 160 to the plasma welding torch power supply unit 100 via a lead-in line 120. The torch receiving device 140 may include a body 142 having a first end 143 for connection to the plasma welding torch lead-in line 120 and a second end 144 defined for connection to the torch body 160 of the plasma arc welding torch 150. The receiving device 140 may include a set of ports 145 defined within the first end 143 of the body 142. The ports 145 may be configured to fluidly connect to a group of fluid passages 122, 124, 126 of the plasma welding torch lead-in line 120. The group of ports 145 typically includes a first plasma gas port 145A and a second plasma gas port 145B. The first plasma gas port 145A may be configured to receive plasma pre-flow gas (e.g., gas 104), and the second plasma gas port 145B may be configured to receive plasma cutting flow gas (e.g., gas 106). The third port 145C may be a protective gas port, configured to receive protective gas (e.g., gas 106).

[0034] Body 142 may define a set of fluid flow paths (e.g., gas channels) 148, substantially disposed within the body, to be fluidly connected via gas ports 145A, 145B, 145C to fluid conduits 122, 124, 126 within the welding torch inlet 120. For example, the body may define a first plasma gas channel 148A connected to gas port 145A, a second plasma gas channel 148B connected to gas port 145B, and a protective gas channel (e.g., protective gas conduit) 148C connected to gas port 145C. As discussed below, the first plasma gas channel 148A and the second plasma gas channel 148B may fluidly connect gas ports 145A and 145B to valve 146 to select between two gases flowing therein. For example, valve 146 can select between two gases flowing in the first plasma gas channel 148A and the second plasma gas channel 148B, and determine which gas can (e.g., via the welding torch gas conduit 149 discussed below) flow onto the welding torch. That is, valve 146 can prevent one of the gases (e.g., the gas in the first plasma gas channel 148A or the gas in the second gas channel 148B) from flowing onto the welding torch, while allowing the other gas to flow onto the welding torch. A shielding gas port 145C can be fluidly connected to a shielding gas conduit 148C formed between a first end 143 and a second end 144.

[0035] The body 142 may be formed of any of a variety of materials. In some embodiments, the body 142 is formed of a substantially insulating material. For example, the body may be made of Ryton / Thermec, Techtron, Torlon, Vespel, or other materials.

[0036] The body 142 has a short length (e.g., shorter relative to other components such as the lead-in line 120). As discussed below, components within the receiving device (e.g., valves) can be used to rapidly extract gas from the torch body 160, allowing one or more material handling procedures (such as torch shutdown procedures (e.g., descent error procedures)) to be initiated in the presence or absence of certain gases. For example, in some embodiments, the body may have a length of less than about 1 foot (e.g., less than about 6 inches) between the first end 143 and the second end 144.

[0037] The receiving device 140 may also include a fluid selection valve (e.g., a three-way multi-port valve) 146 disposed within the body 142 and fluidly connected to a group port 145 to fluidly connect to a first passage 124 and a second passage 126 in the plasma torch lead-in line 120. The valve 146 is configured to fluidly connect the first and / or second passage to a torch gas conduit 149 formed at or near the second end 144. The torch gas conduit 149 delivers the gas selected by the valve 146 to the torch body 160. In some cases, for example, where there is no obstruction between the valve 146 and the plasma chamber, the torch gas conduit 149 is fluidly connected to the torch tip. In some embodiments, the torch gas conduit 149 of the body has a volume of less than approximately 0.3 cubic inches (e.g., between the valve 146 and the torch tip (e.g., between the valve 146 and the outer surface of the downstream second end of the receiving device body)). In some embodiments, the torch gas conduit 149 has a volume of less than approximately 0.2 cubic inches. For example, in some cases, the torch gas conduit volume may be the space defined or enclosed between the valve 146 and the output port 147 of the receiving device (e.g., formed along the outer surface of the second end of the body) that supplies the selected process gas to the torch. This small volume of the torch gas conduit 149 can help provide a rapid gas transition time and reduce (e.g., minimize, eliminate) the negative effects associated with gas pressure decay and prolonged gas pressure decay, such as long descent times. Furthermore, the substantially fixed volume of the torch gas conduit 149 provides stable behavior during the gas transition from the pre-flow to the cutting flow gas during torch ignition, and a stable ratio between gas pressure and current during arc dissipation.

[0038] In some embodiments, the three-way valve 146 is configured to select a gas (e.g., at its inlet ports 145A and / or 145B) from a first passage (e.g., conduit) 124 or a second passage (e.g., conduit) 126, and allows the selected gas to be delivered to the torch body via the torch gas conduit 149. For example, the three-way multi-port valve 146 may be configured to alter (e.g., selectively manipulate) the fluid flow between a first end 143 and a second end 144 of the body to select from primary gases that have entered the group port 145 and are being delivered to the torch gas conduit 149. For example, the valve 146 may be used to fluidly connect a first process gas 104 and a second process gas 106 to the torch gas conduit 149. The valve 146 may also selectively deliver the selected primary gas (e.g., from the first passage 124 or the second passage 126) to the torch via the torch gas conduit 149.

[0039] In addition to supplying gas to the welding torch, valve 146 can also fluidly connect the welding torch gas conduit 149 to a location upstream of the welding torch, such as a power supply unit (e.g., connected to the welding torch manifold 108). This fluid connection to the upstream component can allow venting to atmospheric pressure via the welding torch manifold 108. For example, welding torch line 120 can fluidly connect at least one of the gas passages 148 to the venting atmospheric pressure. For example, gas present in one or more of the fluid passages 122, 124, 126 of line 120 can be vented from the welding torch system via the welding torch manifold 108 and then exit the system (e.g., to the atmosphere) via vent valve 110 (e.g., instead of being entirely vented forward through the welding torch tip). Furthermore, in some embodiments, valve 146 can be used to restrict the flow of gas (e.g., one of the plasma gases (e.g., pre-flow or cutting flow)) into the welding torch gas conduit 149, and thus also restrict its entry into the welding torch body 160. In some cases, excess plasma gas prevented from entering the welding torch gas conduit 149 by the multi-way valve 146 can be discharged upstream through the welding torch inlet pipe 120.

[0040] The multi-way valve 146 may include any of a variety of suitable gas switching valves. The multi-way valve 146 may be configured such that at least one of the process gases (e.g., pre-flow gas or cutting flow gas) is always fluidly connected to the welding torch gas conduit 149. For example, the multi-way valve 146 may be rapidly switched back and forth such that at least one of the gases always flows to the welding torch.

[0041] As mentioned above, the receiving device 140 may be positioned at or near the torch body 160 to quickly and efficiently change or replace the gas (e.g., plasma gas) within the torch. In some embodiments, the multi-way valve 146 may be located at a length 141 less than approximately 12 inches (e.g., less than approximately 6 inches) from the plasma chamber 162 of the plasma arc welding torch body 160. In some embodiments, the valve 146 within the receiving device may be positioned remotely from the power supply unit 100. For example, the valve 146 in the torch receiving device 140 may be at least approximately 2 meters away from the manifold 108 of the plasma cutting system power supply unit 100.

[0042] about Figure 1 The plasma cutting system depicted and described can be implemented in various examples, such as mechanized welding torches or handheld portable welding torches. For example, see reference... Figure 3 In a cross-sectional view, the mechanized welding torch 350 may include a valve 346 to guide one or more processing gases received therein from a power supply unit (such as the power supply unit 100 described above). The welding torch 350 may include a receiving device 340 configured to be coupled to a torch body 360. The receiving device may define ports 345A and 345B, which are connected to processing gas passages 348A and 348B, and allow selected gases to be delivered to the torch body 360 via a torch gas conduit 349. As described in the context, a multi-way valve 346 may be provided within the receiving device 340 to selectively allow gases entering the receiving device through ports 345A, 345B and processing gas passages 348A, 348B to advance to and flow onto the plasma chamber of the welding torch.

[0043] In some aspects, the plasma cutting system described above (e.g., plasma arc welding torch system 50) can be used to select between a group of plasma gases (e.g., pre-flow gas and cutting flow gas) in a torch receiving device (e.g., receiving device 140) that connects a plasma arc welding torch (e.g., welding torch 150) to a torch lead (e.g., welding torch lead line 120), wherein the torch receiving device 140 includes a valve (e.g., multi-way valve 146) configured to manipulate the fluid flow to the plasma arc welding torch (e.g., by selecting between pre-flow gas and cutting flow gas) among the group of plasma gases.

[0044] In some embodiments, an exemplary method may include supplying a pre-flow plasma gas (e.g., from gas 104) through a first conduit (e.g., a first processing gas passage 124) coupled to a torch receiving device, the pre-flow plasma gas traveling through a valve (e.g., valve 146) to the plasma arc welding torch. This may allow the pre-flow gas (such as nitrogen) to flow to the welding torch (e.g., to the plasma chamber of the welding torch).

[0045] In some cases, the method may include igniting a plasma arc within a plasma arc welding torch in the presence of a pre-flowing plasma gas. The torch system can detect or sense the occurrence of ignition and the formation of a plasma arc between the electrode and the torch nozzle.

[0046] When the plasma arc is ignited, the method may include selecting the cutting plasma gas (e.g., from gas 106). For example, the cutting plasma gas can be selected by activating a valve to restrict further downstream flow of the pre-flow plasma gas to the plasma arc torch. Activating the valve also allows the cutting plasma gas to flow through the valve from a second conduit in the torch feeder (e.g., a second processing gas passage 126) to the plasma arc torch. The switch from the pre-flow gas to the cutting flow gas can occur rapidly. Because the receiving device 140 is positioned close to the torch, the change in gas supplied to the torch can be achieved quickly, typically faster than if the gas flow change were directed at the power supply (e.g., only at manifold 108). This is typically because if the gas is switched at or near the torch, the contents of the feeder line do not need to be discharged from the feeder line and through the torch before the gas change can be achieved. As discussed herein, this rapid responsiveness in terms of gas flow can be useful in enacting changes to material handling operations, such as accelerated shutdown procedures. Some tests have shown that the gas descent time can be reduced by approximately 35 milliseconds to approximately 100 milliseconds using the systems and methods described herein. For example, selecting the cutting plasma gas can switch the gas supply at the plasma arc welding torch (e.g., from the torch gas conduit 149) from the pre-flowing plasma gas in the first conduit to the cutting plasma gas in the second conduit in less than approximately 1 second.

[0047] In some embodiments, the method may include discharging a first conduit of the torch lead to a pressure below the pressure of the plasma chamber, such as atmospheric pressure, at a location upstream of the plasma arc welding torch. This may release pre-flow plasma gas from the torch lead. In some cases, discharging the first conduit of the torch lead may include opening a valve within the power supply section of the plasma cutting system to which the torch lead is attached. For example, manifold 108 within the power supply section may be opened to discharge a first processing gas passage 124 to atmospheric pressure. In some cases, this may be performed after the valve has blocked the flow of pre-flow gas and allowed the cutting flow gas to flow to the torch.

[0048] The method may also include using a cutting plasma gas to perform a plasma cutting operation. For example, once the plasma gas is switched from a pre-flow to a cutting flow using, for example, valve 146, the welding torch can use the cutting flow gas as the plasma gas to perform a cutting operation.

[0049] In some embodiments, the method may further include activating a valve (e.g., valve 146) to restrict the flow of cutting plasma gas (e.g., gas 106) further downstream from the second conduit (e.g., the second processing gas passage 126) to the plasma arc welding torch. Activating the valve (e.g., valve 146) may also discharge any remaining cutting plasma gas upstream through the torch inlet and from a manifold (e.g., manifold 108) within the plasma cutting system power supply section to reduce pressure in the plasma arc welding torch. That is, the valve can be switched to prevent further travel of cutting gas to the torch while manifold 108 can be opened to allow any cutting gas present in the inlet line to be discharged from the system. In some embodiments, this may be performed in conjunction with a plasma arc shutdown procedure. In some cases, the method may include activating the valve just before or simultaneously with the start of the plasma arc shutdown procedure.

[0050] Other configurations are feasible. Unless otherwise specified, other exemplary embodiments may include one or more features or components from the examples described above. For example, in some embodiments, valve 146 may be directly connected to the discharge unit. For example, the gas may be modified or controlled at the power supply unit and, for example, supplied to the receiving device 140 via ports 145A and 145B, may be discharged to atmospheric pressure. One or more of the gas delivery methods described herein may be performed using this configuration by discharging at the receiving device rather than at the power supply unit.

[0051] In some embodiments, the plasma cutting system may be configured to have multiple gas flow guiding valves at or near the welding torch. For example, see reference to Figure 2 The plasma cutting system may include a power supply unit 200 with a metering console that provides a set of gas supplies, which may include a protective gas supply unit 202, a first processing gas (e.g., plasma gas (e.g., pre-flow plasma gas)) 204, and a second processing gas (e.g., plasma gas (e.g., cutting flow plasma gas)) 206. The configuration of the different gas supplies may vary based on the desired material handling operation.

[0052] Similar to the above about Figure 1 As described in the example, the plasma cutting system may include a lead-in line 220, which includes a protective gas passage 222, a first processing gas passage 224, and a second processing gas passage 226.

[0053] Valves for controlling the gas may be disposed in or on the welding torch 150, or within another structural member (such as the welding torch receiving device 240). In some embodiments, a multi-way valve (e.g., a three-way valve) 246 may be disposed on or near the welding torch body 160 to selectively deliver the desired process gas to the welding torch, as described above. Furthermore, another valve 247 may be disposed at or near the welding torch, such as between the multi-way valve 246 and the welding torch body 160, to allow or prevent the flow of selected process gas to the welding torch. As shown, valve 247 may also be fluidly connected to the vent 210. During use, valve 247 can therefore be used during transition, start-up, or shutdown procedures to rapidly vent process gas upstream of the welding torch. That is, according to one or more of the methods described herein, valve 247 can improve and accelerate the shutdown procedure by significantly reducing venting time / gas pressure decay and the extraction of gas from the plasma chamber of the welding torch 150.

[0054] While various embodiments are described herein, it should be understood that they are presented and described by way of example only and are not intended to limit the claims presented herein to any particular construction or structural element. Therefore, the breadth and scope of the preferred embodiments should not be limited by any of the exemplary structures or embodiments described above, but should be defined solely by the appended claims and their equivalents.

Claims

1. A plasma arc welding torch system, comprising a plasma arc welding torch and a torch receiving device, wherein the torch receiving device comprises: A body having a first end and a second end, wherein the first end defines a plurality of gas ports fluidly connected to a plurality of gas supply units, and the second end is configured to deliver a plurality of gases from the plurality of gas supply units to the plasma arc welding torch; The gas passage between the gas ports and the gas outlet at the second end of the body; and A valve system, disposed within the body and fluidly connected to the gas passage, for manipulating the airflow of the various gases through the gas passage; The valve system is configured to block at least one flow of at least one of the plurality of gases entering the body, thereby delivering at least one of the plurality of gases to the plasma arc welding torch.

2. The plasma arc welding torch system according to claim 1, wherein, At least one of the gases is a plasma gas.

3. The plasma arc welding torch system according to claim 1, wherein, The valve system includes a multi-way valve.

4. The plasma arc welding torch system according to claim 3, wherein, The multi-way valve is configured to switch between a first gas and a second gas in the plurality of gases in less than about 1 second.

5. A plasma arc welding torch system, comprising a plasma arc welding torch and a torch receiving device, wherein the torch receiving device comprises: A body having a first end and a second end, wherein the first end defines a plurality of gas ports fluidly connected to a plurality of gas supply units, and the second end is configured to deliver a plurality of gases from the plurality of gas supply units to the plasma arc welding torch; The gas passage between the gas ports and the gas outlet at the second end of the body; and A valve system, disposed within the body and fluidly connected to the gas passage, for manipulating the airflow of the various gases through the gas passage; The valve system is configured to select among the plurality of gases entering the plurality of gas ports by selectively blocking at least one gas flow from the plurality of gases entering the body, thereby delivering at least one of the plurality of gases to the plasma arc welding torch.

6. The plasma arc welding torch system according to claim 5, wherein, At least one of the gases is a plasma gas.

7. The plasma arc welding torch system according to claim 5, wherein, The valve system includes a multi-way valve.

8. The plasma arc welding torch system according to claim 7, wherein, The multi-way valve is configured to switch between a first gas and a second gas in the plurality of gases in less than about 1 second.

9. A plasma arc welding torch system, comprising a plasma arc welding torch and a torch receiving device, wherein the torch receiving device comprises: A body having a first end and a second end, wherein the first end defines a plurality of gas ports fluidly connected to a plurality of gas supply units, and the second end is configured to deliver a plurality of gases from the plurality of gas supply units to the plasma arc welding torch; A gas passage between the gas ports and a gas outlet at the second end of the body; A valve system, disposed within the body and fluidly connected to the gas passage, for manipulating the airflow of the various gases through the gas passage; The valve system is configured to select among the plurality of gases entering the plurality of gas ports by selectively blocking at least one gas flow from the plurality of gases entering the body, thereby delivering at least one of the plurality of gases to the plasma arc welding torch; and A discharge valve configured to discharge at least one of the plurality of gases to atmospheric pressure.

10. The plasma arc welding torch system according to claim 9, wherein, At least one of the gases is a plasma gas.

11. The plasma arc welding torch system according to claim 9, wherein, The valve system includes a multi-way valve.

12. The plasma arc welding torch system according to claim 11, wherein, The multi-way valve is configured to switch between a first gas and a second gas in the plurality of gases in less than about 1 second.

13. A method for operating a plasma cutting system by selecting among multiple gases in a torch receiving device, wherein, The welding torch receiving device includes a valve system configured to manipulate the fluid flow to the plasma arc welding torch, and the method includes: The first gas among the multiple gases is supplied to the plasma arc welding torch via the valve system; and The valve system is activated to restrict the further flow of the first gas of the multiple gases to the plasma arc welding torch.

14. The method of claim 13, further comprising supplying a second gas from the plurality of gases to the plasma arc welding torch via the valve system.

15. The method of claim 14, further comprising igniting a plasma arc in the plasma arc welding torch in the presence of the first gas among the plurality of gases.

16. The method of claim 15, further comprising performing a plasma cutting operation using the second gas from the plurality of gases.

17. The method of claim 13, further comprising initiating a plasma arc shutdown procedure.

18. A plasma arc welding torch system, comprising a plasma arc welding torch and a torch receiving device, wherein, The torch receiving device includes a valve system configured to manipulate the fluid flow to the plasma arc welding torch, and the torch receiving device further includes: Devices for supplying a first gas from the plurality of gases to the plasma arc welding torch via the valve system; and Devices for activating the valve system to restrict further flow of the first gas of the plurality of gases to the plasma arc welding torch.

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