Thermo-burner guide gas supply methods and related systems and devices

Abstract

A method (300) for initiating a plasma arc in a plasma cutting system, the method comprising: the provision (302) of a plasma gas supply guide line extending between a power supply and a plasma arc cutting torch, wherein the guide line comprises a first section proximal to the power supply and a second section proximal to the torch and an in-line valve within the guide line between the first section and the second section; the selective closing of the in-line valve by a controller to trap a static volume of gas in the first section (304); the production (306) of a wasteable volume of gas in the second section, and the initiation (308) of the plasma arc when a pressure of the dropable volume reaches a pressure value within a specified range.

Description

TECHNICAL FIELD

[0001] This disclosure relates generally to thermal cutting torches (e.g., plasma arc torches), and more particularly to methods of delivering plasma arc torch gas and related systems and devices. BACKGROUND

[0002] In some conventional plasma cutting systems (e.g., Hypertherm™ Long Life™ plasma arc cutting systems), a plasma arc is typically initiated during a pre-flow gas flow condition and then switched to a cutting flow gas flow condition for cutting a workpiece (e.g., a plate-like workpiece). This operation is typically performed because the gas flow conditions used for proper and reliable plasma arc ignition are often different from those used during steady-state cutting conditions. A valve assembly located relatively close to the torch (e.g., an on / off valve assembly) is typically used to switch between ignition and steady-state cutting. For example, the off-valve assembly includes a manifold and multiple valves (e.g., solenoid valves) to control the plasma gas flow and shield the gas flow to the torch.For plasma gas flow or shield gas flow, there are typically two valves to control the gas flow. For example, one valve may be dedicated to the pre-flow gas flow, and the other valve may be dedicated to the cutting gas flow.

[0003] In some other plasma cutting systems (e.g., Hypertherm non-Long Life plasma cutting systems), substantially all of the gas control functions (i.e., gas control valves) are located in a power supply or gas console to which the torch is connected, which may be located 20 to 150 feet from the torch.

[0004] Known plasma cutting systems are known, for example, from WO 2011 / 082 017 A1, US 2008 / 0 210 670 A1, US 8 258 421 B2 and DE 195 36 150 A1. SUMMARY

[0005] The present invention is defined by the subject matter of the appended claims.

[0006] In some embodiments, a plasma cutting system may include a power supply, a torch, a plasma gas supply conduit extending from a gas supply to the torch and having a first portion proximal to the power supply and a second portion proximal to the torch, an in-line valve positioned in the conduit between the first portion and the second portion, and a controller programmable to control a position of the in-line valve such that the in-line valve is selectively closeable by the controller to (a) trap a static volume of gas in the first portion and (b) establish a ventable volume of gas in the second portion.

[0007] Embodiments may include one or more of the following features.

[0008] The controller may be programmed to initiate the plasma arc when the pressure of the drop-off volume reaches a pressure value within a predetermined range (e.g., in some cases, a lower value of the predetermined range may be approximately 9 psi and an upper value of the predetermined range may be approximately 50 psi). The plasma cutting system may also include a pressure sensor in the second section of the plasma gas supply line. The first section and the second section may be part of a hose that supplies a pilot gas flow and cutting gas flow to the plasma cutting system. The controller may be programmed to vary the pressure of the gas through the plasma gas supply line to the plasma arc torch in a controlled manner to establish a flow rate for cutting after the arc is initiated.In some cases, the controller may be programmed to terminate a plasma arc when a temporary second pressure reaches a predetermined pressure level. The plasma cutting system may also include means for connecting a plurality of gas sources to the plasma arc torch through a plurality of plasma gas supply lines and a plurality of in-line solenoid valves.

[0009] In some embodiments, a method for initiating a plasma arc in a plasma cutting system may include providing a plasma gas supply guide conduit extending between a power supply and a plasma arc cutting torch, where the guide conduit includes a first portion proximal to the power supply and a second portion proximal to the torch, and an in-line valve within the guide conduit between the first portion and the second portion, selectively closing the in-line valve through a controller (i.e., using a controller) to trap a static volume of gas in the first portion; establish a droppable volume in the second portion; and initiate the plasma arc when a pressure of the droppable volume reaches a pressure value within a predetermined range.

[0010] In some embodiments, initiation may be followed by changing one of the in-line valves or a supply valve to a first position, thereby adjusting a flow of gas to the plasma arc cutting torch, establishing a cutting pressure in the second section after a temporary pressure in the second section increases to a cutting pressure level, and increasing a plasma arc current to a predetermined level.

[0011] In some embodiments, the first portion and the second portion may be part of a hose carrying a pilot gas flow and cutting gas flow.

[0012] In some embodiments, the method may also include varying the pressure of the gas through the plasma gas supply conduit to the plasma arc cutting torch in a controlled manner to establish a gas flow rate for plasma cutting after arc initiation.

[0013] In some embodiments, the method may also include connecting a plurality of gas sources to the plasma arc torch through a plurality of plasma gas supply lines, each gas supply line having an in-line solenoid valve.

[0014] In some embodiments, the method may also include controlling the in-line valve with a digital signal processor that provides an output to the in-line valve, such that the in-line valve is controlled based on the output of the digital signal processor.

[0015] In some embodiments, a first position of the in-line valve is open and a second position of the in-line valve is closed, and the method may also include measuring a first time for the pressure in the second section to achieve a measure of a set value for a first known length and inner diameter of the gas in the plasma gas supply guide line, measuring a second time for the pressure in the second section to achieve a measure of a set value for a second known length and inner diameter of the plasma gas supply guide line, and calculating a length of a plasma gas supply guide line based on the difference between the first time and the second time,where the difference between the second time and the first time is proportional to the difference between the volume of gas in the second known length and the first known length of the plasma gas supply guide line.

[0016] In some embodiments, a method of operating a plasma arc torch system may also include changing the in-line valve to a first position, thereby increasing a flow of gas to the plasma arc cutting torch such that a transient pressure in the second section increases prior to pressure dissipation through a plasma chamber of the plasma arc cutting torch, and igniting the plasma arc cutting torch when the transient pressure in the second section reaches a value within the predetermined range.

[0017] In some embodiments, a method of operating a plasma torch system, where the plasma torch system includes a guide line plasma power supply coupled to a torch through a guide line; an in-line valve located in the guide line, and a portion of the guide line between the in-line valve and the torch defining an out-valve hose portion, may include delivering a gas to the torch through the guide line;selectively closing the in-line valve to establish a dissipable volume of gas in the out-valve hose section and initiating a plasma arc in the torch when a pressure of the gas at the torch reaches a pressure value within a predetermined range by: allowing a pressure of a volume of gas trapped between the in-line valve and the torch to dissipate to the pressure valve, or opening the in-line valve to release a volume of gas trapped between an upstream regulating valve and the in-line valve and allowing a pressure of the gas in the out-valve section to increase to the pressure value;

[0018] In some embodiments, the method may also include closing the in-line valve to allow a pressure of a volume of gas trapped in the out-valve portion to drop at a selected rate while ramping down a plasma arc current along with the decreasing pressure.

[0019] In some embodiments, the method may also include varying the pressure of the gas through the plasma gas supply line to the torch in a controlled manner to establish a flow rate of gas for cutting after initiation of the arc.

[0020] In some embodiments, initiating also includes changing one of the in-line valve or a supply valve to a first position, thereby adjusting the flow of gas to the torch; thereby creating a cutting pressure when a temporary second pressure increases to a cutting pressure level, and increasing an arc current to a predetermined level. In some cases, a lower pressure value of the predetermined range may be approximately 9 psi, and an upper pressure value of the predetermined range may be approximately 50 psi.

[0021] In some embodiments, the method may also include connecting a plurality of gas sources to the plasma torch through a plurality of plasma gas supply lines, each having an associated solenoid valve.

[0022] In some embodiments, the method may also include controlling the in-line valve with a digital signal processor that provides an output to the in-line valve, such that the in-line valve is controlled based on the output of the digital processor.

[0023] In some embodiments, a method for initiating a plasma arc in a plasma arc torch may include flowing a plasma gas to the plasma arc torch through a plasma gas supply line and an in-line valve within the gas supply line in a first position; thereby establishing a first pressure in a portion of the gas supply line between the in-line valve and the plasma arc torch, changing the in-line valve to a second position to adjust the flow of plasma gas to the plasma arc torch and establishing a second pressure that varies in the second portion between the in-line valve and the plasma arc torch, and initiating a plasma arc when the varying second pressure reaches a pressure value within a predetermined range.

[0024] In some embodiments, the method may also include increasing the pressure of the plasma gas through the plasma gas supply line to the plasma arc torch in a controlled manner to a cutting flow amount after the initiation of the arc.

[0025] In some embodiments, initiation may also include increasing an arc current to a predetermined level, switching the in-line valve to a first position, thereby adjusting the flow of plasma gas to the plasma torch, and establishing a cutting pressure as the second increases to a stable cutting pressure level. In some cases, a lower value of the predetermined range may be approximately 9 psi, and an upper value of the predetermined range may be approximately 50 psi.

[0026] In some embodiments, the first position of the in-line valve is open and the second position of the in-line valve is closed, and the method may also include measuring a first time for the second pressure to achieve a measure of a predetermined value for a first known length and inner diameter of the plasma gas supply line; measuring a second time for the second pressure to achieve a measure of a second known length and inner diameter of the plasma gas supply line; and calculating a length of the plasma gas supply guide line based on the difference between the second time and the first time, wherein the difference between the second time and the first time is proportional to the difference between the amount of gas in the second known length and the first known length of the plasma gas supply guide line.

[0027] In some embodiments, the method may also include connecting a plurality of gas sources to the plasma arc torch through a plurality of plasma gas supply lines, each having an associated in-line solenoid valve.

[0028] In some embodiments, the method may also include controlling the in-line valve with a digital signal processor that provides an output to the in-line valve, such that the in-line valve is controlled based on the output from the digital signal processor.

[0029] In some embodiments, a method for initiating a plasma torch system including a torch connected to a torch through a plasma power supply coupled to the guide conduit, an in-line valve located in the guide conduit, and a portion of the guide conduit defining an out-valve hose section may include delivering a gas to the torch through the guide conduit, closing the in-line valve to establish a drop-in volume of gas in the out-valve hose section, and initiating a plasma arc in the torch while the in-line valve is closed.

[0030] In some embodiments, the method may also include connecting a plurality of gas sources to the plasma arc torch through a plurality of plasma gas supply lines, each having an in-line solenoid valve.

[0031] In some embodiments, the method may also include controlling the in-line valve with a digital signal processor that provides an output to the in-line valve, such that the in-line valve is controlled based on the output from the digital signal processor.

[0032] In some embodiments, initiation also includes changing the in-line valve to a first position, adjusting the flow of gas to the torch, creating a cutting pressure when the temporary pressure in the out-valve section increases to a cutting pressure level, and increasing an arc current to a predetermined level.

[0033] In some embodiments, the method may also include varying the pressure of the gas through the guide conduit to the torch in a controlled manner to establish a flow rate for cutting after initiation of the arc.

[0034] In some embodiments, a first position of the in-line valve is open and a second position of the in-line valve is closed, and the method may also include measuring a first time for a pressure in the out-valve hose section to achieve a measure of a predetermined first known length and inner diameter of the guide conduit; measuring a second time for a pressure in the out-valve hose section to achieve a measure of a predetermined second known length and inner diameter of the guide conduit; and calculating a length of the gas supply guide conduit based on the difference between the second time and the first time, where the difference between the second time and the first time is proportional to the difference between the amount of gas in the second known length and the first known length of the plasma gas supply guide conduit.

[0035] Embodiments may include one or more of the following advantages.

[0036] In some embodiments, the thermal torch delivery systems described herein may exhibit a smaller delay in an effective transition from arc ignition to cutting than observed in some other torch systems, such as torch systems that have substantially all gas control valves located in the power supply. For example, in such systems that have substantially all gas control valves located in the power supply, the large volume of the torch guides between the control valves and the torch may result in a delay (i.e., a significant delay) in the torch gas when gas flows are changed (e.g., changing from the induction gas flow to the cutting gas flow).

[0037] In some cases, effective control of gas flow within the burner guides using valves in the power supply can be complicated by the fact that the volume of gas varies between different burners, which have different guide lengths. The variable delays in gas pressures in burner systems, all of which have gas control valves in their power supply, can affect both arc initiation and arc shutdown processes, resulting in premature consuming damage and an increase in misfires and start-up irregularities. The delay in the change in gas flow can be exacerbated when attempting to reignite a burner after a misfire, particularly when using a hand-held torch, since the pressure in the burner typically must be vented before re-ignition can be attempted.

[0038] By placing an in-line valve within the torch guide, as described herein, these delay problems can be limited (e.g., prevented in some cases). For example, in some cases, placing a single in-line valve near the torch can reduce the volume of gas that must be expelled from the guide line during the transition from ignition to cutting. The reduction in volume between the valve and the torch can result in a reduction in the delay in the time required to effectively transition between ignition and cutting. Limiting the delay in adjusting the gas pressure can result in a plasma arc torch that is more reliable and easier to operate than some other torch systems.

[0039] Furthermore, by reducing the delay in transitioning between arc ignition and cutting, the single-valve gas delivery systems described herein can help provide better control of gas flow near the torch and accommodate changes in gas pressure within the torch (e.g., rapid changes in gas pressure) during arc initiation and arc shutdown than some other torch systems.

[0040] In some embodiments, the gas delivery systems described herein may require fewer components (e.g., fewer gas valves and / or gas delivery lines) within the torch than some other torch systems, such as torch systems having multiple gas delivery lines. For example, some of the gas delivery systems described herein include an in-line valve (i.e., only one in-line valve) for delivering plasma gas and / or shield gas, which is typically integrated as part of a torch guide line. As a result of reducing the need for additional gas control components (e.g., an off-valve assembly), the gas delivery systems described herein may help reduce the overall cost of a torch system on which the gas delivery system is used.Additionally, the gas delivery system described herein can help reduce system installation time by reducing the number of gas delivery valves and hoses included in a burner assembly, as additional off-valve assemblies typically do not need to be attached to or connected to the power supply.

[0041] In some embodiments, the gas delivery systems described herein can be used to more easily determine the length of a burner gas line than with some other burner systems. Additionally, the gas delivery systems described herein can be used to more easily detect gas leaks within a burner gas line than with some other burner systems.

[0042] Furthermore, in some embodiments, the thermal torch guide gas delivery systems described herein can be used more effectively in underwater cutting than some other torch systems. For example, using the in-line valve, water present in the torch can be removed by flowing gas through the out-valve hose and the torch before initiating a cutting arc. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side view of an exemplary plasma arc torch system having a gas supply guide source with an in-line gas valve for regulating gas flow to a torch. Fig. Figure 2 is a schematic diagram of an exemplary plasma arc torch system having a gas supply guide line with an in-line valve. Fig.Figure 3 is a flow diagram describing an exemplary plasma arc ignition sequence using a guide line having an in-line valve. Fig. Figure 4A is a timing diagram of gas pressures within a guide conduit and plasma arc current during an exemplary plasma arc ignition sequence. Fig. Figure 4B is another timing diagram of gas pressures within a guide conduit and plasma arc flow during an exemplary plasma arc ignition sequence. Fig. 5 is a flow diagram describing another exemplary plasma arc ignition sequence using a guide line having an in-line valve. Fig. Figure 6 is a timing diagram of gas pressures within a guide conduit and a plasma arc stream during another exemplary plasma arc ignition sequence. Fig.7 is a flow diagram describing another exemplary plasma arc ignition sequence using a guide line having an in-line valve. Fig. 8 is a flow diagram describing another exemplary plasma arc ignition sequence using a guide line having an in-line valve. Fig. Figure 9 is a timing diagram of gas pressures within a guide conduit and a plasma arc stream during an exemplary plasma arc quenching sequence. Fig. Figure 10 is a timing diagram of gas pressures within guide lines having different lengths during exemplary pressure build-up test sequences. DETAILED DESCRIPTION

[0043] In some designs, thermal burner systems which have burners connected to burner control units by gas supply lines which have in-line valves to selectively reduce the gas pressure within the burner result in a burner system which is more reliable and easier to control than some other burner systems.

[0044] Referring to Fig.1, a thermal torch system (e.g., a plasma arc torch system) 50 may include a portable (e.g., handheld) plasma arc torch 100 and a plasma arc cutting control system (e.g., a torch control unit) 200. The plasma arc torch 100 is connected to the torch control unit 200 by a generally flexible gas supply conduit 150 extending from a gas supply of the torch control unit 200 to the torch 100. The gas supply conduit 150 is used to supply electrical power (i.e., electrical power to establish a plasma arc for cutting) to the torch for use. In some embodiments, the gas supply guide line 150 provides both a pilot gas flow and a cutting gas flow to the torch 100.

[0045] The guide line 150 includes a first gas hose section 152, a second gas hose section (e.g., off-valve hose) 154 proximal to the torch 100, and a gas valve (e.g., an in-line valve) 156 disposed between and fluidly connecting the first gas hose section 152 and the off-valve hose 154. The off-valve hose 154 typically has a length 155 that is less than a length 153 of the first gas hose section 152. In some embodiments, as discussed herein, by placing the in-line valve 156 near the burner 100 (e.g., about two inches to about 12 feet from the burner), and at a constant distance from the burner 100 (i.e.,The in-line valves are substantially equidistant from respective torches having guide lines of different lengths), the length 153 of the first gas hose section 152 can be varied between different torches (e.g., torches with different guide line lengths) without significantly affecting the timing of critical gas transitions (e.g., during arc ignition) in the torch. For example, as discussed below, if the out-valve hose 154 is of a constant length, a variety of different guide lines having different overall lengths (e.g., different first gas hose sections having different lengths) can typically utilize the same torch control unit and control settings without fundamental changes to the plasma arc ignition sequence.

[0046] The out-valve hose 154 and the first gas hose section 152 can be any of various lengths. For example, in some embodiments, the length 155 of the out-valve hose 154 is typically less than 6 feet. However, the first gas hose section 152 can be any of various lengths based on the user's needs. For example, in some embodiments, the length 153 of the first gas hose section 152 can be about 1 foot to about 100 feet (e.g., about 1 foot to about 75 feet, about 1 foot to about 50 feet, about 1 foot to about 25 feet). In the example shown, the length 153 of the first gas hose section 152 can be about 20 feet to about 150 feet.

[0047] The guide conduit 150 (i.e., the first gas hose sections 152 and the off-valve hose 154) can be formed from any of a variety of structurally and chemically suitable materials. For example, rubber, plastic, metal braid, composite, or any of various combinations of these materials can be used. In the example shown, the gas hose sections 152 and the off-valve hose 154 are made of nylon.

[0048] The in-line valve 156 is configured to regulate and control flow with the guide line, for example, selectively limiting the flow of gas from the first gas tube section 152 into the out-valve tube 154 (e.g., during arc ignition or extinguishing sequences). In some cases, the in-line valve 156 may seal the first gas tube section 152 from the out-valve tube 154 to create a trapped volume of gas within the first gas tube section 152.

[0049] The in-line valve 156 may be any of various types of valve devices suitable for limiting gas flow within the guide conduit 150. In some embodiments, the in-line valve 156 may transition between a first, open position and a second, closed position to open or enclose the first gas tube portion 152. Alternatively or additionally, in some embodiments, the in-line valve 156 may open or close proportionally to create various openings of different sizes through which gas may pass. In some cases, such proportional valves may provide more flexibility and increase control when transitioning between arc ignition and steady-state cutting and when adjusting the gas pressures supplied to the torch.

[0050] Examples of such suitable valve devices may include plunger valves, butterfly valves, ball valves, gate valves, check valves, and other types of valve devices. The in-line valve 156 is typically electronically controlled (e.g., controlled by the burner control unit 200) to regulate gas flow through the guide line 150. For example, in the Fig. 1 illustrates the in-line valve 156 in the form of a two-way solenoid valve.

[0051] As in Fig.1, in some embodiments, a pressure sensor 158 is mounted within the off-valve hose 154 (e.g., near the burner) between the in-line valve 156 and the burner 100. In some cases, the use of one or more pressure sensors may allow for more accurate pressure delivery to the burner 100 and also allow for better troubleshooting techniques. The pressure sensor 158 is configured to measure the gas pressure within the off-valve hose 154 and transmit the gas pressure data to the burner control unit 200 (e.g., a power supply controller). In some embodiments, a pressure sensor is alternatively or additionally mounted in the first gas hose section 152.

[0052] Pressure sensor 158 may be any of various types of fluid pressure sensing devices, including piezoresistive strain gauge devices, capacitive pressure sensing devices, electromagnetic pressure sensing devices, piezoelectric pressure sensing devices, optical pressure sensing devices, potentiometric pressure sensing devices, or various other types of pressure sensing devices. For example, pressure sensor 158 may be a PSE540 pressure sensing device from SMC Corporation of America (Noblesville, IN).

[0053] During use, the plasma arc torch 100 can generate a plasma arc for cutting a workpiece when the plasma arc torch 100 is electrically and fluidly connected to the torch controller 200 via the guide conduit 150. The plasma torch 150 generally includes a torch body 105 defining a plasma gas flow path for directing a plasma gas to a plasma chamber in which the plasma arc is formed. An electrode (not shown) is mounted within the torch body 105 to create the plasma arc. A nozzle (not shown) with a central exit opening is mounted relative to the electrode at a distal end 110 of the torch body 105. The plasma arc torch 100 also includes a shield 115 mounted relative to an outer surface of the nozzle at the distal end 110 of the torch body 105 to prevent exposure of the nozzle and electrode to molten workpiece material (e.g.,splashes) or other deposits. The burner 100 includes a connector 102 for connection to the guide line 150. The connector 102 may be a permanent connection or, alternatively, may be a temporarily securable connector (e.g., a detachable coupling).

[0054] Portable plasma arc torches may be trigger-activated devices. This means that the torch 100 generates a plasma stream in response to the operator triggering a trigger 120 mounted in the torch housing 125. Optionally, a removable safety device 130 may be mounted adjacent to the front surface of the trigger 120 to prevent the trigger 120 from inadvertently starting the plasma arc torch.

[0055] The plasma arc torch 100 may be attached to the torch control unit 200 at a connection area 210, for example, via a connector 202, which may include, for example, electrical connections and gas flow lines. The connectors 102, 202 may be movable to allow easy maneuverability of the portable plasma arc torch.

[0056] The torch control unit 200 includes an outer housing 205, which may house a power supply, a gas source (e.g., a gas pressure regulator) 206, and a controller 204. The controller 204 may typically be used to control the operation of the torch system 50, including, for example, the gas flow and electricity supplied to the torch 100. To do so, the torch unit is in communication (e.g., wired, electrical, or wireless communication) with the various components of the torch 100 and the guide conduit 150. For example, the controller 204 may be in communication with the in-line valve 156, the one or more pressure sensors 158 mounted within the guide conduit 150, the torch electrode, and other components used to ignite the plasma arc and operate the torch for cutting.

[0057] To selectively adjust the gas pressure within the off-valve tube 154 (and within the torch), the controller 204 may be programmable to control a position of the in-line valve 156 so that the controller 204 can adjust the in-line valve to one or more different configurations. For example, the controller 204 may move the in-line valve 156 to a closed position to trap a static volume of gas in the first gas tube section 152 and establish a ventable volume of gas in the off-valve tube 154. In some embodiments, as discussed below, the controller 204 is programmed to initiate the plasma arc when a pressure of the ventable volume reaches a pressure value within a predetermined range.As discussed further below, the controller 204 is programmed to vary the pressure of the gas supplied through the gas supply conduit 150 to the plasma arc torch 100 (e.g., within the torch) in a controlled manner to establish a desired flow rate for cutting after arc initiation.

[0058] As discussed further below, the torch system 50 described herein may alternatively or additionally utilize the gas supply guide line 150, which has the in-line valve 156, to extinguish a plasma arc based on the pressure in the out-valve hose 152. In some embodiments, the controller 204 is programmed to terminate a plasma arc when a temporary second pressure in the out-valve hose (i.e., and in the torch 100) reaches a predetermined pressure level. In some cases, the controller 204 is a processor (e.g., a digital signal processor).

[0059] The torch control unit 200 may include a control panel 215, which includes a user-activated switch 213 and a user interface 225 that can be used to operate the torch system 50. The control panel 215 may also include, for example, an error light 230 (e.g., an LED indicator light), a power / pressure selector button 235, a dial 240, and / or a cutting-type knob 245. Although certain features of the control panel 215 are shown utilizing knobs and buttons, any type of mechanism, for example, dials, knobs, buttons, slide rails, toggle levers, touch screens, switches, or any combination thereof, may be used. A display mounted on the control panel 215 may provide a user with information about the portable plasma arc cutting system 200 and may have at least two states.An operating state may indicate operating data about the plasma arc cutting system 200, for example, cutting current, gas pressure, gas flow rate, cutting type, or any combination thereof. A service state may indicate error data about the plasma arc cutting system, for example, error codes.

[0060] While the torch system 50 is generally illustrated and described as having only one gas supply conduit 150, other configurations are possible. For example, in some embodiments, the torch system 50 includes means for connecting a plurality of gas sources to the plasma gas torch (e.g., through a plurality of plasma gas supply conduits and a plurality of in-line solenoid valves).

[0061] While the systems and methods described herein have generally been described with reference to portable-type burners, other configurations are possible. For example, in some embodiments, the burner system includes other types of burner systems, such as automated, mechanized burners (i.e., burners connected to a scaffolding device).

[0062] Fig. Figure 2 is a schematic diagram of a hardware arrangement of a thermal torch system (e.g., the plasma arc torch 50) illustrating a gas flow path from a gas source to a plasma arc torch. Referring to Fig.2, gas, such as plasma cutting gas (e.g., oxygen, nitrogen, or a mixture of oxygen, nitrogen, or other gases), is supplied from a gas source (e.g., cylinder or compressor) 208 and is regulated at a set pressure by a gas pressure regulator (or metering valve) 206 on a gas console (e.g., within control unit 200). For example, gas pressure regulator 206 may be configured to supply gas to guide line 150 at pressures ranging from approximately 50 psi to 120 psi (e.g., approximately 60 psi to approximately 80 psi).

[0063] From the gas pressure regulator 206, the gas flows through the first gas hose section 152, which can be any of various lengths (e.g., approximately 20 feet to approximately 150 feet long). As discussed above, a pressure sensor 158 can be mounted within the first gas hose section 152. At the end of the first gas hose section 152, the gas flows through the in-line valve 156, which can be in the form of a solenoid valve (e.g., a programmable, electrically controlled solenoid valve). As discussed above, the in-line valve can open and close to limit or permit the flow of gas into the out-valve hose 154. Gas flows from the in-line valve 156 to the out-valve hose 154 and then to the burner 100.

[0064] When closed during operation, the in-line valve 156 creates a volume (i.e., a static volume) of gas within the out-valve tube 154. When the in-line valve 156 is closed, the closure can also create a decayable volume of gas within the out-valve tube 154. That is, when the in-line valve 156 is closed, gas ceases to flow into the out-valve tube 154, so that as the gas that was previously within the out-valve tube 154 flows out (e.g., through the burner 100), the volume of gas as well as the gas pressure within the out-valve tube 154 decreases (drops).

[0065] Based on this expected relationship between the closure of the in-line valve 156 and the pressure of the gas within the out-valve tube 154 (and the torch 100), the in-line valve can be selectively opened and closed during operation to vary the gas pressure within the out-valve tube 154. Varying the gas pressure within the out-valve tube can be used in several useful ways for the operation of a plasma arc torch. Example arc ignition method

[0066] In some embodiments, the plasma arc system described herein can be used to perform multiple plasma arc ignition sequences. For example, in certain embodiments, by closing the in-line valve to interrupt a relatively high cutting flow pressure, low pre-flow pressure conditions can be created within the out-valve hose during startup of the plasma arc torch, and the arc can be initiated while the pressure in the torch is decreasing. For example, (briefly Fig.1), if the user attempts to operate the plasma torch 100, for example, by positioning the distal end 110 of the torch housing 105 proximal to a workpiece to be cut, the user may then pull the trigger 120 for use. The pulled trigger 120 may then send a signal to the control unit 200 (e.g., the controller 204) to ignite a plasma arc. Once such an ignition signal is received, the controller 204 may operate the operating system 50 (e.g., the in-line valve 156 and the electrode) to perform one of the various plasma arc operations discussed herein (e.g., ignition).

[0067] Referring to Fig.3, in an example plasma arc ignition method (300), a torch system is first provided (302) including a gas supply guide line (e.g., guide line 150) having an in-line valve (e.g., in-line valve 156). The in-line valve separates a first gas hose section (e.g., first gas hose section 152) and a second gas hose section (e.g., out-valve hose 154). In some embodiments, the first gas hose section and the second gas hose section are components of a gas delivery hose that carries both a pilot gas flow and a cutting gas flow from a plasma torch control unit to a plasma torch.

[0068] Next, a volume of gas is substantially trapped within the first gas tube section (304). For example, in some embodiments, the in-line valve is closed (e.g., using a controller), trapping a static volume of gas (e.g., gas flowing from the gas regulator 206) within the first gas tube section.

[0069] A decayable volume of gas is then created in the second gas tube section (306). For example, in some embodiments, when the in-line valve is closed (e.g., as discussed above, relative to trapping a static volume of gas in the first gas tube section), the gas ceases to flow into the second gas tube section, resulting in the decay of the volume of gas in the second gas tube section as the gas flows to the burner. As the decayable volume of gas within the second gas tube section decreases, the pressure within the second gas tube section (and therefore also within the burner) also decreases substantially proportional to the volume.

[0070] Next, a plasma arc may be initiated (308). For example, when the pressure of the gas within the second gas hose section drops to a pressure level (e.g., a threshold pressure level) within a predetermined pressure range, the plasma arc may be ignited (e.g., by using a power supply controller). The predetermined range of gas pressure at which the arc can be ignited may vary based on the type and size of the torch used. For example, in some cases, a lower pressure value of the predetermined range is approximately 9 psi and an upper pressure value of the predetermined range is approximately 50 psi (e.g., approximately 9 psi to approximately 50 psi). However, the plasma arc may also be ignited at other pressures.

[0071] In some embodiments, the method also includes varying the pressure of the gas through the plasma gas supply conduit to the plasma arc cutting torch in a controlled manner to establish a gas flow rate for plasma cutting after arc initiation. For example, after the plasma arc is ignited, the in-line valve may be opened so that the gas flows from the gas pressure regulator through the first gas hose section, through the second gas hose section, and into the torch for plasma cutting. With the in-line valve reopened, the pressure of the gas flowing through the torch may be increased to a pressure close to or at the pressure supplied by the pressure regulator for cutting.However, in some cases the gas pressure in the burner may be lower than the gas pressure supplied by the pressure regulator, for example as a result of the length of the gas supply line.

[0072] In some cases, the method also includes connecting a plurality of gas sources to the plasma arc cutting torch through a plurality of plasma gas supply lines. Each plasma gas supply line may have its own associated in-line valve (e.g., a solenoid valve). By using a plurality of gas supply lines, a plurality of gases can be selectively supplied to the torch for use.

[0073] In some embodiments, the method also includes controlling the in-line valve with the processor (e.g., a digital signal processor) providing an output to the in-line valve such that the in-line valve can be controlled based on the output from the digital signal processor.

[0074] The method may also include (e.g., after the arc is initiated) changing one of the two in-line valves or supply valves to a first position (e.g., an open position), thereby establishing a flow of gas to the plasma arc cutting torch that establishes a cutting pressure in the second gas hose section after a temporary pressure in the second gas hose section increases to a cutting pressure level, and increasing a plasma arc current to a predetermined level (e.g., a cutting current). For example, in certain embodiments, after establishing the pilot arc, the in-line valve may be opened to rapidly provide cutting flow gas pressures to the torch as a result of the increasing gas pressure in the pilot line (e.g., the out-valve hose). Therefore, the arc can be ignited at a current which is lower than the desired cutting current (e.g.approximately 20 A to approximately 50 A), while the pressure in the outlet valve hose is less than the desired cutting pressure (e.g., approximately 9 psi to approximately 50 psi). After the arc is ignited, the pressure and plasma arc current can then be increased to the desired cutting parameters, for example, a cutting current of approximately 50 A to approximately 400 A and a cutting pressure of approximately 50 psi to approximately 100 psi.

[0075] The method can also be used to estimate the length of the guide conduit. For example, in some embodiments, a first position of the in-line valve is an open position and a second position of the in-line valve is a closed position. In such embodiments, the method can further include measuring a first time for the pressure in the second section to reach a measure of a predetermined value for a plasma gas supply guide conduit having a first known length and inner diameter. That is, the known length and inner diameter can be those of an example guide conduit to which the estimated guide conduit length can be compared.The method then includes measuring a second time for the pressure in the second section to achieve a measure of a predetermined value for a second known length and inner diameter of the gas supply guide conduit. Using the measured first time and the measured second time, a length of the plasma gas supply guide conduit can be estimated (e.g., calculated) based on the difference between the second time and the first time. For example, the difference between the second time and the first time is typically proportional to the difference between the amount of gas in the second known length and the first known length of the plasma gas supply guide conduit.

[0076] In some embodiments, the method may further include changing the in-line valve to a first (open) position, thereby increasing a flow of gas to the plasma arc cutting torch such that a temporary pressure in the second gas hose section grows prior to pressure dissipation through a plasma chamber of the plasma arc cutting torch. Subsequently, the plasma arc cutting torch may be ignited when the temporary pressure in the second section reaches a pressure value within the predetermined range. For example, in some embodiments, if a pilot arc is not established (e.g., the arc misfires) before the pressure in the torch drops to a value that is too low (e.g., below the predetermined pressure range), the in-line valve may be reopened (e.g.,quickly reopened) to fill the out-valve tube with gas, and then closed to repeat the ignition procedure. Fig. Figure 4B, for example, shows an example timing diagram illustrating such example arc ignition sequences.

[0077] The arc ignition method 300 may also include one or more additional steps or features as discussed herein with reference to the other example torch operating methods and procedures.

[0078] Fig. 4A is an example timing diagram illustrating an example arc firing sequence as discussed relative to the methods 300 discussed above. More specifically, Fig.4A the gas pressure within the first gas hose section P1, the pressure in the out-valve hose P2, and the arc current I. As shown, at any time t1, both the valve on the gas console (e.g., gas pressure regulator) and the in-line valve are open. With both valves open, gas can be supplied to the torch at or close to the pressure of the gas released by the pressure regulator. As shown, in some cases, with both valves open, the pressure in the out-valve hose P2 is lower than the pressure within the first gas hose section P1, for example, as a result of pressure drop across the length of the gas supply guide line.

[0079] At a time t2, the in-line valve is closed, and as a result, the pressure in the out-valve hose P2 begins to drop. As a result, the pressure in the out-valve hose P2 (and also in the plasma torch) also begins to drop. When the pressure in the out-valve hose P2 reaches a predetermined pressure value (e.g., a threshold pressure value), the controller (e.g., via an ignition console) can attempt to ignite an arc within the plasma torch, for example, by applying a current to the electrode. At a time t3, the arc can be ignited (reflected by the increase in current I), and the in-line valve reopens to transition to cutting parameters.As a result of the opening of the in-line valve, the gas pressure in the out-valve tube P2 (and therefore in the torch) increases rapidly and essentially equalizes to its steady-state pressure value at or near the pressure in the first gas tube section P1. Additionally, after the in-line valve is open, the arc current I is also increased to a predetermined set operating value (e.g., cutting current).

[0080] In some cases, it is possible that at time t3, the out-valve pressure is too low to allow arc ignition, and the arc is not ignited. Therefore, if this occurs, the in-line valve can be reopened to increase the pressure in the out-valve tube P2, and the process described above can be repeated. For example, such a repeated process is Fig. 4b illustrates, in which the in-line valve at t 1a , t 1b , t 1c , t1d , t 1e , t 1f opens and at t 2a , t 2b , t 2c , t 2d , t 2e closes. In the example shown, the arc ignition failed several times before the arc was successfully ignited at t 3f was ignited.

[0081] An advantage of igniting the plasma arc in this manner is that a reduced pressure in the off-valve hose P2, which is more ideal for ignition, can be delivered without the use of a separate control unit and additional gas hoses (e.g., a hose dedicated solely to delivering a gas at an ignition pressure). Additionally, these processes can be performed without the long and variable delay that can be caused when making pressure or flow adjustments in the control unit or gas console as a result of the relatively short, known length of the off-valve hose. Furthermore, the transition from the lower ignition pressure to the higher cutting pressure can typically be made much faster than if the change were made in the remote control unit or power supply. Example of arc ignition process

[0082] Fig.5 is a flowchart illustrating another exemplary plasma arc torch operation method (500). In some embodiments, the torch operation method may be performed using a plasma arc torch system (e.g., the plasma arc torch system 50 discussed above).

[0083] First, gas is supplied (502) to a plasma torch (e.g., torch 100) through the gas supply guide line (e.g., guide line 150). The gas supply guide line may include, for example, an in-line valve (e.g., in-line valve 156) separating a first gas hose section (e.g., first gas hose section 152) and a second gas hose section (e.g., out-valve hose 154). By using the gas supply guide line, gas (e.g., cutting gas) may flow from a gas source (e.g., via control unit 200 and gas regulator 206) and through the guide line to the torch.

[0084] Next, the in-line valve may be closed to establish a drop-off volume of gas in the out-valve tube (504). In some cases, the in-line valve may be controlled with a processor, such as a digital signal processor (e.g., controller 204), that provides an output to the in-line valve, such that the in-line valve is controlled based on the output from the digital signal processor. After the in-line valve is closed, the plasma arc may then be ignited (506). For example, the plasma arc may be ignited once the pressure in the out-valve tube drops to a pressure value within a predetermined range (508), similar to method 300 discussed above.

[0085] Alternatively, in some embodiments, the in-line valve may be closed so that substantially all of the plasma gas can escape the out-valve tube. Then, after substantially all of the gas has escaped the out-valve tube, the in-line valve may be opened to increase the pressure within the out-valve tube, for example, to the pressure value within the predetermined range for arc ignition (510). Brief reference to Fig. 6 the arc can be ignited by selectively increasing the pressure within the off-valve hose P2 to a desired pressure value.

[0086] In some embodiments, initiating the plasma arc also includes changing one of the in-line valves or supply valves in the pressure regulator to a first position (i.e., an open position), thereby adjusting the flow of gas to the torch, creating a cutting pressure when a temporary second pressure increases to a cutting pressure level, and increasing an arc current to a predetermined level.

[0087] The in-line valve can also be used to adjust the pressure of the gas supplied to the torch after arc ignition. For example, in some embodiments, the method further includes varying the pressure of the gas supplied through the plasma gas guide line to the torch in a controlled manner to establish a flow rate for cutting after arc initiation.

[0088] The predetermined gas pressure range within which the arc can be ignited can vary depending on the type and size of the torch used. For example, in some cases, the lower pressure value of the predetermined range is approximately 9 psi, and the upper pressure value of the predetermined range is approximately 50 psi.

[0089] In some examples, the method may also include connecting multiple gas sources to the plasma arc torch through a plurality of gas supply lines, each having an associated linear solenoid valve. By using multiple gas supply lines, multiple gases can be selectively supplied to the torch for use.

[0090] The arc ignition process 500 may also include one or more additional steps or features as discussed herein with respect to the other example torch operating methods and procedures.

[0091] Fig. 6 is a timing diagram illustrating an exemplary arc ignition sequence as discussed relative to the method 500 discussed above. More specifically, Fig. 6 the gas pressure within the first gas pressure section P1, the pressure in the off-valve tube P2 and the arc current I during an arc ignition sequence according to method 500.

[0092] As in Fig.As shown in Figure 6, at a time t1, both the valve on the gas console and the in-line valve are closed. As a result, the gas trapped in the gas hose has a certain pressure P1, and the gas in the out-valve hose P2 is at approximately ambient pressure, since the in-line valve limits the gas from the gas console from entering the out-valve hose P2. At a time t2, the in-line valve is opened, and gas begins to flow from the gas hose into the out-valve hose. As a result, the pressure in the out-valve hose P2 (and thus also into the burner) begins to rise from ambient pressure. In a short time, the pressure in the off-valve hose P2 reaches a maximum value and starts to fall, while the entire volume of trapped gas in the guide (i.e. the gas in the gas hose and off-valve hose together) flows out of the burner.When the pressure in the burner drops to a predetermined threshold, the ignition console attempts to ignite the arc. At t3, the arc is ignited and the gas valve on the gas console opens.

[0093] With the arc ignited and the gas valve on the gas console open, the arc current can be increased to a predetermined set value, for example, while the gas pressure is quickly increased to the desired cutting pressure. The trapped pressure value in the gas hose P1 and the timing of the valve opening in the gas console can be adjusted to optimize the timing of the desired pressure-timing curve to increase torch operation (e.g., arc ignition reliability). Other example arc ignition methods

[0094] Fig.7 is a flowchart illustrating another exemplary plasma arc ignition method (700). In some embodiments, the arc ignition method (700) may be performed using a plasma arc torch system (e.g., the plasma arc torch system 50 discussed above).

[0095] First, a plasma gas may be flowed (702) to a plasma arc torch (e.g., torch 100) through a gas supply line (e.g., guide line 150) having an in-line valve (e.g., in-line valve 156) configured in a first, open position, thereby creating a first pressure in a portion of the plasma gas supply line between the in-line valve and the plasma arc torch (e.g., out-valve hose 154). For example, with the in-line valve open, the pressure within the out-valve hose may be at or near the same pressure of the gas being expelled from a pressure regulator into the first gas hose section as a result of the out-valve hose being liquid open and connected to the first gas section.

[0096] Next, the configuration of the in-line valve can be changed to a second, closed position to adjust the flow of plasma gas to the plasma gas torch (704). As a result of the in-line valve closing, a second pressure can be created within the out-valve tube that varies over time. For example, once the in-line valve is closed, the pressure within the out-valve tube can decrease over time as a result of a decreasing volume of gas within the out-valve tube.

[0097] When the varying second pressure reaches a pressure value within a predetermined range, the plasma arc may be initiated (706). For example, when the second pressure reaches a pressure value within a predetermined range (e.g., approximately 9 psi to approximately 90 psi), the torch system controller may signal the electrode to ignite (e.g., send an electrical current to the electrode).

[0098] The arc ignition method 700 may also include one or more additional steps or features as discussed herein with respect to the other example torch operating methods and procedures.

[0099] Fig.8 is a flowchart illustrating yet another exemplary plasma arc ignition method (800). In some embodiments, the arc ignition method (800) may be performed using a plasma arc torch system (e.g., the plasma arc torch system 50 discussed above).

[0100] First, a gas (e.g., a plasma / cutting gas) is supplied (802) to a torch (e.g., torch 100) through a gas supply guide line (e.g., guide line 150) having an in-line valve (e.g., in-line valve 156). For example, gas may be supplied from the gas console (or gas pressure regulator) 206 of a torch control unit 200.

[0101] Next, a drop-in volume of gas may be created (804) in an out-valve tube (e.g., the out-valve tube 156). For example, the in-line valve may be closed to limit gas from flowing from the first gas tube section 152 into the out-valve tube 154. As a result, the volume of gas in the out-valve tube begins to decrease (drop) as gas flows from the out-valve tube and subsequently into and out of the burner (e.g., the burner 100).

[0102] The plasma arc may then be initiated while the in-line valve is closed (806). For example, once the in-line valve is closed and the pressure within the out-of-line valve tube is expected to drop to a pressure level (e.g., a threshold pressure) within a predetermined pressure range, the arc may be initiated. In some embodiments, when the second pressure reaches a desired pressure value within a predetermined range (e.g., approximately 9 psi to approximately 50 psi), the torch system controller may signal the electrode to ignite (e.g., send an electrical current to the electrode).

[0103] The arc ignition method 800 may also include one or more additional steps or features as discussed herein with reference to other example torch operating methods and procedures.

[0104] After the arc is initiated using one or more of the methods described above, in some embodiments, the pressure of the plasma gas through the plasma gas supply line to the plasma arc torch may be increased in a controlled manner to a cutting flow rate after arc initiation. For example, with the arc initiated, the in-line valve may be opened (or left open (or further opened)) in ignition processes where the in-line valve is opened during initiation, allowing the gas pressure within the out-valve tube (and therefore also within the torch) to increase (e.g., increased to a desired cutting pressure).

[0105] In some embodiments, the methods may also include increasing an arc current to a predetermined level, changing the in-line valve to a first, open position to adjust the flow of plasma gas to the plasma arc torch, and establishing a cutting pressure when the second pressure (e.g., the pressure in the out-valve hose) increases to a stable cutting pressure level.

[0106] The methods may also include connecting multiple gas sources to the plasma arc torch through a plurality of gas supply lines, each having an associated linear solenoid valve. By using multiple gas supply lines, multiple gases can be selectively supplied to the torch for use.

[0107] In some embodiments, the method also includes controlling the in-line valve with a processor (e.g., a digital signal processor) that provides an output to the in-line valve such that the in-line valve can be controlled based on the output from the digital signal processor. Deleting a sheet

[0108] In some embodiments, the pressure of the gas in the out-valve tube and the plasma arc current can be reduced to extinguish the plasma arc. For example, the in-line valve can be closed to allow a volume of gas trapped in the out-valve tube to decrease (fall) at a desired rate while the plasma current (e.g., ramping down (e.g., ramping down in a step sequence)) also decreases along with the decreasing pressure.

[0109] Fig.9 is a timing diagram illustrating an exemplary arc extinguishing sequence using a plasma torch system (e.g., torch system 100) having a torch (e.g., torch 100) with a gas supply guide line (e.g., guide line 150) having an in-line valve (e.g., in-line valve 156). More specifically, Fig. 9 a gas pressure within a first gas hose section P1, a pressure in the off-valve hose P2 and an arc current I.

[0110] As illustrated, during use (e.g., a cutting operation), the pressure in the out-valve tube P2 is at or near the pressure within the first gas tube section P1 because the in-line valve is open, so that the first gas tube section and the out-valve tube are open and fluidly connected. However, as mentioned above with respect to the arc ignition process, during a steady-state cutting operation, the pressure in the out-valve tube P2 may be less than the first gas tube section P1 as a result of pressure loss (e.g., pressure drop) as the gas flows through the gas supply guide line. As illustrated, at t4, the in-line valve can be closed, so that the pressure in the out-valve tube P2 (and therefore the pressure in the torch) begins to drop, while the volume of gas in the out-valve tube decreases. As shown, the arc current can be ramped down (e.g.,down at intervals) so that the arc current and the pressure in the out-valve hose P2 are reduced accordingly.

[0111] For example, in some embodiments (briefly referring to Fig. 1) When a user releases the trigger 120 to stop a cutting operation, a controller (e.g., controller 204) signals the in-line valve 156 and the torch power supply to both reduce the gas pressure entering the torch 100 and reduce the plasma arc current at the electrode. In some cases, the controller 204 may close the in-line valve 156 while substantially simultaneously reducing the electrical current sent to the electrode. Burner guide length scanning

[0112] In some embodiments, a length of the gas supply guide line (e.g., a length 153 of the first gas hose section 152) may be determined by monitoring (e.g., measuring) the pressure in the guide line (e.g., the pressure within the first gas section 152) during filling or emptying of the guide line (e.g., the first gas hose section 152) and then comparing the rate of pressure change within the first gas hose section to that of known guide lengths. Alternatively, a time period for a measured pressure within the first gas hose section to drop to a determined pressure may also be used to estimate the guide line length.

[0113] More specifically, it is generally expected that burner guides having longer first gas hose sections will require longer periods of time to pressurize the first gas hose section to a desired pressure at or near that of the gas supply (e.g., the gas pressure regulator 206). Therefore, by monitoring the time required to pressurize the first gas section, the length can be estimated. In some cases, the controller of the control unit may monitor the pressure within the first gas hose on a time-based basis and compare the measured pressure to known time-pressure profiles (e.g., by consulting a lookup table or database) to estimate a guide line length. Such length information may be taken into account by the controller when selecting the guide line (e.g., the first gas hose section) for use (e.g.,the ignition methods described herein). For example, in some cases, the length information can be used to determine desired pressure compensations (e.g., the pressure loss through the entire guide line) or timing compensations for opening and closing the in-line valve to change the pressure within the out-valve tube (and in the burner).

[0114] Additionally, by periodically using the in-line valve 156 and pressure sensors 158 to determine the volume of the first gas hose section and the corresponding length, the pressure compensation desired to deliver constant burner pressures can be adjusted to account for variations such as minor guide restrictions or leaks in addition to normal variations.

[0115] In some embodiments, this process can be tracked at regular intervals and over time to warn or notify the user of gradual or sudden changes in the gas hose volume characteristics. Such changes could serve as an indicator that the gas hose is leaking or otherwise damaged.

[0116] For example, in some embodiments, one or more of the torch operating or ignition methods described above may further include measuring a first time for the second pressure (e.g., the pressure in the off-valve hose) to achieve a measure of a set value for a first known length and inner diameter of the plasma gas supply line, and measuring a second time for the second pressure to achieve a measure of a set value for a second known length and inner diameter of the plasma gas supply line.After the first time and the second time are measured, a length of the gas supply guide line can be calculated based on the difference between the second time and the first time, where the difference between the second time and the first time is proportional to the difference between the amount of gas in the second known length and the first known length of the plasma gas supply guide line.

[0117] For example, illustrated Fig. Ten test results in the form of a timing diagram reflecting how the total length of the torch guide affects the time required to pressurize a first gas hose section. Specifically, a 25-foot first gas hose section and a 100-foot first gas hose section were pressurized using a gas console, and the increasing internal pressure of the first gas hose section P1 over time was measured.

[0118] As in Fig.As shown in Figure 10, at a time t1, both the valve on the gas console and the in-line valve were closed, so that the gauge pressure P1 within the first gas hose section was 0. At a time t2, the valve on the gas console was opened while the in-line valve was kept closed. After the valve on the gas console was opened, the internal pressure of the first gas section P1 increased rapidly for both guide lengths. At a time t3, the internal pressure P1 of the 25-foot-long first gas hose section reached 90% of the previously set value (e.g., the pressure of the gas pressure produced by the gas console). However, as shown, for the 100 ft hose, it took until a time t4 (i.e., which was longer than time t3) for the internal pressure of the first gas hose section P1 to reach 90% of the previously set predetermined value.The observed difference between t3 and t4 is expected to be due to the difference in gas hose volume capacity, which is directly proportional to gas hose length. This means that since there is a larger volume within a larger gas hose, additional time is typically required to fill the larger volume with a sufficient volume of gas to increase the pressure. Therefore, by monitoring the time required for the internal pressure of a gas hose section P1 to reach 90% of the predetermined set value for any burner guide length, the burner gas guide length can be identified (e.g., estimated using an observed pressure profile). The observed test results for the test described above are shown below in Table 1. Table 1 Gas hose size Pre-determined fixed pressure Time to reach 90% of the previously set pressure 25 ft long 0.165" ID 45 psi t3-t2=0.402 sec 100 ft long 0.165" ID 45 psi t4-t2=1.510 sec

[0119] Similar techniques can be used to identify other gas hose lengths, such as 50 foot and 75 foot hoses.

[0120] A torch length determination procedure can also be performed by monitoring the time difference for depressurizing a previously pressurized gas hose by keeping the valve on the gas console closed and opening the in-line valve. However, in some cases, depressurization rates can be affected by the types of consumables installed on the torch (e.g., consumable orifice sizes); therefore, this procedure may require additional testing to adequately determine length if the consumable type is unknown.

[0121] Additionally or alternatively, instead of identifying which known length of gas hose is likely installed, the pressure data could also be used to provide individual pressure compensation based on the actual gas volume estimate. This could compensate for small restrictions or leaks and allow the pressure in the burner to be controlled more consistently over time and between different systems. Burner leak detection

[0122] In some embodiments, plasma arc torch systems (e.g., torch system 50) having a gas supply guide line (e.g., guide line 150) with an in-line valve (e.g., in-line valve 156) may also be used for gas leak detection. For example, as shown in Fig.As illustrated in Figure 10, at time t5, the internal pressure of the first gas hose section P1 reaches a steady-state level for both the 25 ft gas hose and the 100 ft gas hose, although, as explained above, steady-state pressure is reached much earlier for the 25 ft hose. If both valves are closed at time t5, after the steady-state pressure is reached, the internal pressure of the first gas hose P1 can be measured after a time interval (e.g., at time t6) and compared with the value at t5. If the measured pressures at times t6 and t5 are essentially the same, then it can be easily estimated that there is little or no leakage between the valve on the gas console and the in-line valve. However, if a drop in the internal pressure of the first gas tube section P1 is observed between time t5 and time t6, then a leak may be present in the gas tube.

[0123] The terminology used herein is for the purpose of describing particular embodiments and is not intended to limit the described systems and methods. As used herein, the singular forms ("a," "an," and "the") are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and / or "include," when used herein, indicate the presence of said features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0124] It will be understood that although the terms first, second, third, etc. are used herein to describe various constraints, elements, components, regions, layers, and / or portions, these constraints, elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are used only to distinguish one constraint, element, component, region, layer, and / or portion from another constraint, element, component, region, layer, and / or portion. Therefore, a first constraint, element, component, region, layer, and / or portion discussed below could be called a second constraint, element, component, region, layer, and / or portion without departing from the teachings of the present invention.

[0125] It will be further understood that when an element is referred to as being 'on' or 'connected' or 'coupled' to another element, it may be directly on or through, or connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being 'directly on' or 'directly connected' or 'directly coupled' to another element, no intervening elements are present. Other words used to describe relationships between elements should be interpreted in the same way (e.g., 'between' versus 'directly between'; 'adjacent' versus 'directly adjacent', etc.).When an element is referred to herein as being 'above' another element, it may be above or below the other element and may either be directly coupled to the other element, or intervening elements may be present, or the elements may be spaced apart by a void or gap.

Claims

[1] A method (300) for initiating a plasma arc in a plasma cutting system, the method comprising: providing (302) a plasma gas supply guide line extending between a power supply and a plasma arc cutting torch, the guide line comprising a first section proximal to the power supply and a second section proximal to the torch and an in-line valve within the guide line between the first section and the second section; selectively closing the in-line valve by a controller to trap a static volume of gas in the first section (304); producing (306) a droppable volume of gas in the second section, and initiating (308) the plasma arc when a pressure of the droppable volume reaches a pressure value within a specified range. [2] The method (300) of claim 1, wherein (a) the first section and the second section are part of a hose carrying a pilot gas flow and a cutting gas flow, (b) the introductory step is followed by the steps: Changing one of the in-line valve or a supply valve to a first position, thereby adjusting a flow of gas to the plasma arc cutting torch; Producing a cutting pressure in the second section after a temporary pressure in the second section increases to a cutting pressure level and Increasing a plasma arc current to a predetermined level, or (c) a first position of the in-line valve is open and a second position of the in-line valve is closed, further comprising: Measuring a first time for the pressure in the second section to determine a measure of a set value for a first known length and inner diameter of the gas in the plasma gas supply guide line; Measuring a second time for the pressure in the second section to determine a measure of a set value for a second known length and inner diameter of the gas in the plasma gas supply guide line and Calculating a length of the plasma gas supply guide line based on the difference between the second time and the first time, wherein the difference between the second time and the first time is proportional to the difference between the amount of gas in the second known length and the first known length of the plasma gas supply guide line. [3] The method (300) of claim 1 or 2, further comprising one of the steps: (a) varying the pressure of the gas through the plasma gas supply guide line to the plasma arc cutting torch in a controlled manner to establish a gas flow rate for plasma cutting after initiation of the arc, (b) connecting a plurality of gas sources to the plasma arc cutting torch through a plurality of plasma gas supply lines, each plasma gas supply line having an in-line solenoid valve, (c) controlling the in-line valve with a digital signal processor providing an output to the in-line valve, such that the in-line valve is controlled based on the output from the digital signal processor, or (d) changing the in-line valve to a first position, thereby increasing the flow of gas to the plasma arc cutting torch so that a transient pressure in the second section increases prior to pressure dissipation through a plasma chamber of the plasma arc cutting torch, and igniting the plasma arc cutting torch when the transient pressure in the second section reaches a value within the predetermined range. [4] A plasma cutting system comprising: a power supply, a burner (100), a plasma gas supply guide line (150) extending from a gas supply to the torch (100) and having a first portion (152) proximal to the power supplier and a second portion (154) proximal to the torch (100) and an in-line valve (156) positioned in the guide line (150) between the first section (152) and the second section (154), a controller (204) programmed to control a position of the in-line valve (156) such that the in-line valve (156) is selectively closeable by the controller (204) to (a) trap a static volume of gas in the first section (152) and (b) establish a ventable volume of gas in the second section (154), wherein (a) the controller (204) is programmed to initiate the plasma arc when a pressure of the drop-off volume reaches a pressure value within a predetermined range, (b) the first section (152) and the second section (154) are part of a hose which provides a pilot gas flow and cutting gas flow to the plasma cutting system, or (c) the controller (204) is programmed to vary the pressure of the gas through the plasma gas supply guide line (150) to the plasma arc torch (100) in a controlled manner to establish a flow rate for cutting after initiation of the arc. [5] The plasma cutting system of claim 4, further comprising at least one of the following: (a) a pressure sensor (158) in the second section (154) of the plasma gas supply guide line (150), (b) means for connecting a plurality of gas sources to the plasma arc torch (100) through a plurality of plasma gas supply lines and a plurality of in-line solenoid valves. [6] The plasma cutting system of claim 4, wherein the controller (204) is programmed to terminate a plasma arc when a temporary second pressure reaches a predetermined pressure level. [7] A method (500) for operating a plasma torch system, the plasma torch system including a plasma power supply coupled to a torch by a guide line, an in-line valve located in the guide line, and a portion of the guide line between the in-line valve and the torch defining an out-valve hose portion, the method comprising: supplying (502) a gas to the burner through the guide line, selectively closing (504) the in-line valve to produce a drop-off volume of gas in the out-valve hose section and initiating (506) a plasma arc in the torch when the pressure of the gas at the torch reaches a pressure value within a predetermined range, by: allowing (508) a pressure of a volume of gas trapped between the in-line valve and the burner to reduce to the pressure value, or when the predetermined pressure range is undershot, reopening (510) the in-line valve to release a volume of gas trapped between an upstream regulating valve and the in-line valve and allowing a pressure of the gas in the out-valve section to increase to the pressure value. [8] The method (500) of claim 7, further comprising one of the steps: (a) closing the in-line valve to allow a pressure of a volume of gas trapped in the out-valve section to drop at a selected rate along with the falling pressure during the ramp-down of a plasma arc current, (b) varying the pressure of the gas through the plasma gas supply line to the torch in a controlled manner to establish a flow rate of gas for cutting after initiation of the arc, (c) connecting a plurality of gas sources to the plasma arc torch through a plurality of plasma gas supply lines, each having an associated in-line solenoid valve, or (d) controlling the in-line valve with a digital signal processor providing an output to the in-line valve such that the in-line valve is controlled based on the output from the digital signal processor. [9] The method (500) of claim 7 or 8, wherein the initiating step further comprises: Changing one of the in-line valve or a supply valve to a first position, thereby adjusting the flow of gas to the burner; The creation of a cutting pressure when a temporary second pressure increases to a cutting pressure level and increasing an arc current to a predetermined level. [10] The method (500) of claim 9, wherein a lower pressure value of the predetermined range is about 9 psi and an upper pressure value of the predetermined range is about 50 psi. [11] A method (700) for initiating a plasma arc in a plasma arc torch, the method comprising: flowing (702) a plasma gas to the plasma arc torch through a plasma gas supply line and an in-line valve within the plasma gas supply line in a first position, thereby creating a first pressure in a portion of the plasma gas supply line between the in-line valve and the plasma arc torch; changing (704) the in-line valve to a second position to adjust the flow of plasma gas to the plasma arc torch and to create a second pressure which changes over time in the section between the in-line valve and the plasma arc torch, and initiating (706) a plasma arc when the changed second pressure reaches a pressure value within a predetermined range. [12] The method (700) of claim 11, further comprising at least one of the steps: (a) after initiation of the arc, controlled increase of the pressure of the plasma gas in the plasma arc torch to a cutting flow rate, (b) connecting a plurality of gas sources to the plasma arc torch through a plurality of plasma gas supply lines, each having an associated in-line solenoid valve, or (c) controlling the in-line valve with a digital signal processor providing an output to the in-line valve such that the in-line valve is controlled based on the output from the digital signal processor. [13] The method (700) of claim 11 or 12, wherein (a) the initiation step further comprises the steps: Increasing an arc current to a predetermined value; Changing the in-line valve to a first position, thereby adjusting the flow of plasma gas to the plasma arc torch, and establishing a cutting pressure when the second pressure increases to a predetermined pressure value, or (b) the first position of the in-line valve is open and the second position of the in-line valve is closed, which further comprises: Measuring a first time for the second pressure to determine a measure of a set value for a first known length and inner diameter of the plasma gas supply line; Measuring a second time for the second pressure to determine a measure of a set value for a second known length and inner diameter of the plasma gas supply line, and calculating a length of the plasma gas supply guide line based on the difference between the second time and the first time, wherein the difference between the second time and the first time is proportional to the difference in the amount of gas in the second known length and the first known length of the plasma gas supply guide line. [14] The method (700) of claim 13, wherein a lower value of the predetermined range is approximately 9 psi and an upper value of the predetermined range is approximately 50 psi. [15] A method (800) for initiating a plasma torch system comprising a plasma power supply coupled to a torch by a guide line, an in-line valve located in the guide line, and a portion of the guide line between the in-line valve and the torch including an out-valve hose portion, the method comprising: supplying (802) a gas to the burner through a guide line, closing (804) the in-line valve to create a drop-off volume in the out-valve tube section, and initiating (806) a plasma arc in the torch while the in-line valve is closed. [16] The method of claim 15, further comprising one of the steps of: (a) connecting a plurality of gas sources to the burner through a plurality of guide lines, each of which has an in-line solenoid valve, (b) controlling the in-line valve with a digital signal processor providing an output to the in-line valve such that the in-line valve is controlled based on the output from the digital signal processor, or (c) varying the pressure of the gas through the guide line to the torch in a controlled manner to establish a flow rate for cutting after initiation of the arc. [17] The method (800) of claim 15 or 16, wherein (a) the preliminary step further comprises the steps: Changing the in-line valve to a first position to adjust the flow of plasma gas to the plasma arc torch; Establishing a cutting pressure when the temporary pressure in the out-valve hose section increases to a cutting level, and Increasing an arc current to a specified level, or (b) a first position of the in-line valve is open and a second position of the in-line valve is closed, further comprising: Measuring a first time for a pressure in the out-valve hose to determine a measure of a set value for a first known length and inner diameter of the guide line; Measuring a second time for the second pressure to determine a measure of a set value for a second known length and inner diameter of the guide line, and Calculating a length of the plasma gas supply guide line based on the difference between the second time and the first time, wherein the difference between the second time and the first time is proportional to the difference in the amount of gas in the second known length and the first known length of the plasma gas supply guide line.

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