Gas cutting device

Abstract

To provide a gas cutting device that uses gas containing hydrogen as fuel gas, can detect leakage of the hydrogen gas, and has high safety.SOLUTION: In a gas cutting device, a body part includes: a support base; a torch that can be moved on the support base along the support base; a fuel gas pipe which is connected to the torch; and a hood which is fixed to the support base and covers the upper side of the support base. The fuel gas pipe has a first opening / closing part that switches between a state of supplying fuel gas to the torch and a state of not supplying the fuel gas to the torch. The hood includes a second opening / closing part provided at a position higher than a roof surface of the hood, and a sensor arranged below the second opening / closing part and detects hydrogen gas. When the sensor detects hydrogen gas, the first opening / closing part is closed into a state where no fuel gas is supplied to the torch.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a gas shut-off device.

Background Art

[0002] Gas shut-off devices equipped with a mechanism for detecting gas leakage are known. This type of technology is described in, for example, Patent Document 1. Patent Document 1 describes that in a gas shut-off device, a plurality of on-off valves and sensors are provided in a gas supply pipe. In the gas shut-off device of Patent Document 1, a sensor for detecting the flow of gas is arranged in a section partitioned by an on-off valve in the gas supply pipe. By comparing the opening / closing condition of the on-off valve and the signal output from the sensor, the presence or absence of gas leakage is determined. That is, when it is detected that gas is flowing when it should not be flowing, it is determined that gas is leaking from the pipe.

[0003] [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​Patent Document 1 describes placing a sensor in a specific section of a gas supply pipe, but it is preferable to be able to detect gas leaks over a wider area, not just a specific section. Furthermore, the gas detection device in Patent Document 2 creates an airflow in a specific direction. While such a gas detection device is useful when the device installed below is a fixed device such as a valve stand, it may be difficult to apply to devices where the piping or nozzle moves while operating, such as a gas cutting device.

[0006] One of the purposes of this disclosure is to provide a gas cutting device that uses a hydrogen-containing gas as a fuel gas, which is capable of detecting hydrogen gas leaks and is highly safe. [Means for solving the problem]

[0007] A gas cutting device according to this disclosure includes a first rail extending in a first direction and a main body that can travel on the first rail. The main body includes a support base extending in a direction intersecting the first direction, a torch supported on the support base and movable along the support base, a fuel gas pipe connected to the torch, and a hood fixed to the support base and covering the upper part of the support base. The fuel gas pipe includes a first opening / closing section for switching between a state in which fuel gas is supplied to the torch and a state in which fuel gas is not supplied to the torch. The hood includes a second opening / closing section provided at a position higher than the roof surface of the hood, and a sensor positioned below the second opening / closing section for detecting hydrogen gas. When the sensor detects hydrogen gas, the first opening / closing section is closed, and fuel gas is not supplied to the torch. [Effects of the Invention]

[0008] According to this disclosure, a gas cutting device that uses a gas containing hydrogen can be provided that can detect hydrogen gas leakage and is highly safe. [Brief explanation of the drawing]

[0009] [Figure 1]Figure 1 is a perspective view of a gas cutting apparatus according to an embodiment. [Figure 2] Figure 2 is a plan view showing the main body of a gas cutting device according to an embodiment. [Figure 3] Figure 3 is a cross-sectional perspective view of the hood of a gas cutting device according to an embodiment. [Figure 4] Figure 4 is a schematic diagram showing the piping system of a gas cutting device according to an embodiment. [Figure 5] Figure 5 is a flowchart showing the operation of the gas cutting device according to the embodiment. [Figure 6] Figure 6 is a flowchart showing the operation of the gas cutting device according to the embodiment. [Figure 7] Figure 7 is a flowchart showing the operation of the gas cutting device according to the embodiment. [Figure 8] Figure 8 is a schematic diagram showing the piping system of a gas cutting device according to an embodiment. [Modes for carrying out the invention]

[0010] [Summary of the Embodiment] First, embodiments of the cutting apparatus according to this disclosure will be listed and described. A gas cutting device according to this disclosure includes a first rail extending in a first direction and a main body that can travel on the first rail. The main body includes a support base extending in a direction intersecting the first direction, a torch supported on the support base and movable along the support base, a fuel gas pipe connected to the torch, and a hood fixed to the support base and covering the upper part of the support base. The fuel gas pipe includes a first opening / closing section for switching between a state in which fuel gas is supplied to the torch and a state in which fuel gas is not supplied to the torch. The hood includes a second opening / closing section provided at a position higher than the roof surface of the hood, and a sensor positioned below the second opening / closing section for detecting hydrogen gas. When the sensor detects hydrogen gas, the first opening / closing section is closed, and fuel gas is not supplied to the torch.

[0011] To address the need to reduce CO2 emissions, studies are underway to use hydrogen gas as a fuel gas in gas cutting of steel. Compared to other fuel gases, hydrogen has a lower gas density and a wider explosive range in air. Therefore, it is desirable that gas cutting equipment using hydrogen gas maintains safety even in the event of a hydrogen gas leak. Accordingly, a gas cutting equipment equipped with a mechanism to detect hydrogen gas leaks was investigated. A configuration was found in which a hood is provided above a support base that supports a reciprocating torch, and a sensor for detecting hydrogen gas is provided on top of the hood. Furthermore, a configuration was found in which the supply of hydrogen gas is stopped when the sensor detects hydrogen gas.

[0012] The gas cutting device according to this disclosure comprises a rail extending in the direction of a first axis (X-axis) and a torch supported on a support base supported by the rail, which reciprocates along the direction of a second axis (Y-axis) intersecting the first axis. The gas cutting device according to this disclosure, by providing a hood that covers the top of the support base, can detect hydrogen gas leaking from near the torch or from piping connected to the torch, even in a gas cutting device that moves in the XY axis direction, without providing a large mechanism that covers the entire range of movement. Due to its low density, hydrogen gas rises quickly in the air. Therefore, leaked hydrogen gas can reach the hood in a short time and be detected by the sensor. In addition, when hydrogen gas is detected, the supply of hydrogen gas is stopped. With these configurations, even if a leak occurs, it can be quickly detected and stopped. Thus, the gas cutting device according to this disclosure can provide a gas cutting device that can detect hydrogen gas leaks and is highly safe.

[0013] In the gas cutting device, when the sensor detects hydrogen gas, the second opening / closing part can be opened. The second opening / closing part is provided in the hood and is an opening / closing part provided at a position higher than the roof surface of the hood. By opening the second opening / closing part at this position, the hydrogen gas collected in the hood can be discharged from the inside of the hood to the outside. According to this configuration, it is possible to prevent the leaked and collected hydrogen from staying in the hood and reaching a high concentration, and further ensure safety.

[0014] In the gas cutting device, the first rail includes a pair of rails that are parallel to each other, and both ends of the support base can be supported by the respective rails of the pair of rails. According to such a configuration, even in a so-called portal-type large gas cutting device in which the support base is supported by a pair of rails, the steel material can be safely cut using a fuel gas containing hydrogen gas.

[0015] In the gas cutting device, the hood includes a roof surface including an inclined portion inclined to be higher toward the central portion, and a cylindrical portion protruding upward from the uppermost portion of the roof surface, and the second opening / closing part and the sensor are arranged inside the cylindrical portion. According to this configuration, hydrogen gas can be efficiently collected in the hood, and in case of a leak, the hydrogen gas can be quickly detected and the collected hydrogen gas can be discharged from the upper part of the hood.

[0016] The gas cutting device may include a plurality of columns extending upward from the support base between the support base and the hood, and the hood may be supported by the plurality of columns. According to this configuration, a highly safe gas cutting device can be provided even when using hydrogen gas without impairing the working efficiency in a conventional gas cutting device. In addition, the hood can be easily attached and detached according to the usage mode of the gas cutting device and requirements.

[0017] [Specific examples of embodiments] Next, a specific embodiment of the gas cutting device according to the present disclosure will be described while referring to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated. In this specification, "hydrogen gas" means a gas composed of hydrogen and inevitable impurities. In this specification, in order to distinguish it from a mixed gas, hydrogen gas that is not a mixed gas may be referred to as 100% hydrogen gas. However, 100% hydrogen gas does not mathematically strictly mean a gas composed of 100% hydrogen, but generally includes gases commercially available as hydrogen gas.

[0018] (Configuration of Gas Cutting Device) FIG. 1 is a perspective view showing the entirety of a gas cutting device 1 according to the present disclosure. Referring to FIG. 1, the gas cutting device 1 includes a traveling unit 10, a main body unit 20, and a mounting unit 60. In FIG. 1, the direction in which the traveling unit 10 extends is shown as the X-axis direction, the width direction of the main body unit 20 is shown as the Y-axis direction, and the height direction of the gas cutting device 1 is shown as the Z-axis. In the following description, the explanations will be based on these axial directions. Also, in the following description, "upward" indicates the + direction of the Z-axis, and "downward" indicates the - direction of the Z-axis.

[0019] Referring to FIG. 1, the traveling unit 10 includes a base 11 and a rail 12 as a first rail fixed to the upper surface of the base 11. The main body unit 20 is provided on the rail 12. The main body unit 20 is capable of reciprocating along the X-axis direction on the rail 12. The main body unit 20 includes a support base 21, a plurality of torches 30 capable of reciprocating along the width direction (Y-axis direction) of the main body unit 20 on the support base 21, and a hood 50 covering the upper side of the support base 21. The gas cutting device 1 can move the torch 30 in the X-Y direction to cut the steel material S placed on the mounting unit 60.

[0020] The running section 10 includes a pair of bases 11 and a pair of rails 12, which are installed parallel to each other. The main body 20 includes a support base 21 and a pair of legs 22 provided below both ends of the support base 21. That is, the support base 21 is supported on the rails 12 via the legs 22. The main body 20 is configured in a gate shape by the support base 21 and the legs 22. The support base 21 extends in the Y-axis direction, i.e., in the direction intersecting the rails 12. The support base 21 extends in a direction perpendicular to the rails 12.

[0021] Figure 2 is a plan view showing the main body 20 of the gas cutting device 1. Referring to Figure 2, the support base 21 is equipped with a traverse rail 23. Multiple carriages 24 are arranged on the traverse rail 23. The carriages 24 reciprocate along the traverse rail 23 by a drive device 75. In Figure 2, only a portion of the drive device 75 is shown. A torch 30 is mounted on each of the carriages 24. The torch 30 comprises a blowpipe 31 and a nozzle 32 attached to the end of the blowpipe 31. The blowpipe 31 is held in a holder 33. The holder 33 is connected to an upper / lowering device 34. Multiple hoses (not shown) serving as fuel gas and oxygen gas piping are connected to the blowpipe 31 via fittings. The hoses connected to each of the torches 30 are housed in a hose cover 40. The hoses are connected to the fuel gas and oxygen gas piping housed inside a piping cover 41 (Figure 1). Solenoid valves are provided in both the fuel gas piping and the oxygen gas piping within the piping cover 41. The fuel gas piping and the oxygen gas piping are each connected to fittings located in the gas control box 42. A solenoid valve is provided in the fuel gas piping within the gas control box 42 as a first on / off section. A solenoid valve is also provided in the oxygen gas piping within the gas control box 42. By opening and closing the solenoid valves provided in the fuel gas piping, it is possible to switch between a state in which fuel gas is supplied to the torch 30 and a state in which fuel gas is not supplied to the torch 30. In the gas cutting device 1, when the sensor 81 (Figure 3) provided in the hood 50 detects hydrogen, the solenoid valve provided in the control box 42 is closed.

[0022] Referring to Figures 1 and 2, a hood 50 is fixed to the support base 21, spaced upward from the support base 21 and covering the area above the support base 21. The hood 50 includes a roof section 51, a cylindrical section 52 as a tube section, and a support column 53. When the roof section 51 is viewed planar in the height direction (Z-axis direction), it has a rectangular shape. The dimensions of the roof section 51 along the width direction (Y-axis direction) are approximately the same as the width direction dimensions of the support base 21. The dimensions of the roof section 51 along the depth direction (X-axis direction) are such that they cover the area from the torch 30 to the piping cover 41, that is, the area above where the torch and piping are located. In other words, the roof section 51 is positioned to cover the torch 30, the hose connected to the torch 30, and the piping connected to the hose. Note that, as shown in Figure 2, if the torch 30 is located near the end of the traverse rail 23, a part of the hose cover 40 may be located outside the area covered by the roof section 51.

[0023] The support columns 53 are fixed to the support base 21. Specifically, the support columns 53 on both ends of the roof section 51 are fixed to the end face covers 28 of the support base 21. The support columns 53 on the rear side of the roof section 51 are fixed to the rear of the support base 21. Note that the support columns 53 are not limited to being directly attached to the support base 21, but may also be fixed to the support base 21 via brackets, extension members, etc. Furthermore, the support columns 53 may include a height adjustment mechanism. The height of the hood 50 can be set according to the overall size of the device and other configurations, and is not particularly limited as long as the hydrogen detection effect is obtained. For example, the lower end of the roof section 51 may be set to a height of 1000 to 1500 mm above the position of the traverse rail 23.

[0024] Figure 3 is a cross-sectional perspective view of the upper part of the hood 50. Referring to Figures 2 and 3, the roof portion 51 of the hood 50 includes a roof surface 55 that slopes overall so as to become higher towards the center, and a skirt portion 56 that hangs down from the outer edge of the roof surface 55. A cylindrical portion 52 is provided in the center of the roof surface 55, projecting upward from the roof surface 55. Inside the cylindrical portion 52 are a solenoid valve 72 as a second opening / closing part and a sensor 81 which is a sensor for detecting hydrogen gas. The sensor 81 is installed below the solenoid valve 72. The opening / closing of the cylindrical portion 52 is switched by opening and closing the solenoid valve 72. The tip of the cylindrical portion 52 may be open to the atmosphere, or exhaust piping may be connected to it. The cylindrical portion 52 is the exhaust port of the hood 50. In the hood 50, the solenoid valve 72 is provided at a position higher than the roof surface 55. The solenoid valve 72 may be provided at the tip of the cylindrical portion 52. Furthermore, a cylindrical section for connecting an exhaust pipe may be provided above the solenoid valve 72. The solenoid valve 72 is closed while gas cutting is being performed without any abnormalities, and opens when the sensor 81 detects hydrogen gas. When the solenoid valve 72 opens, the hydrogen gas accumulated in the roof section 51 is discharged from the hood 50. Naturally, not only hydrogen gas but also various gases lighter than air are discharged in the same way. Forced exhaust can also be performed using an exhaust device or fan.

[0025] The shape of the roof surface 55 is not limited to the forms shown in Figures 1 to 3. For example, only a part of the roof surface may be inclined, the entire roof surface may be composed of a surface without inclination, or it may include a curved surface. Also, a groove for guiding gas may be formed in a part of the roof surface. Furthermore, the cylindrical portion 52 is not limited to being located in the center of the roof. It may be provided at a location other than the center, taking into consideration the flow of gas and wiring. The cylindrical portion 52 may be cylindrical with a rectangular cross-section, or it may have a large diameter portion that serves as a gas retention area.

[0026] In addition to the sensor 81 provided in the hood 50, the gas cutting device 1 may also be equipped with other sensors for detecting hydrogen gas. For example, a hydrogen gas detection sensor can be provided near the gas supply cylinder connected to the gas cutting device 1, or near the connection point where the cylinder connects to the main unit 20 (for example, inside the gas control box 42).

[0027] In Figures 1-3, a gantry-type CNC cutting machine is shown as gas cutting device 1, but the gas cutting device according to this disclosure is not limited to this. For example, a frame planer, a template tracing cutting machine, etc., may also be used.

[0028] (Fuel gas used in gas cutting equipment) In the gas cutting device 1, a gas containing hydrogen is used as the fuel gas. The hydrogen-containing gas may be 100% hydrogen gas or a mixed gas containing hydrogen. The gas mixed with hydrogen is not particularly limited as long as the necessary combustion performance can be obtained, but typically examples include acetylene gas, propane gas, propylene gas, ethylene gas, methane gas, butane gas, and mixed gases thereof, which are flammable gases lighter than air. Specifically, for example, in addition to 100% hydrogen gas, a mixed gas containing 2 to 12 volume percent of ethylene relative to hydrogen gas (for example, "Hydrocut®" manufactured by Iwatani Gas Co., Ltd.) can be used as the fuel gas for the gas cutting device according to this disclosure.

[0029] (Piping for gas cutting equipment) Figure 4 is a schematic diagram showing the piping 101 in the gas cutting apparatus according to this disclosure. The gas cutting apparatus according to this disclosure, as shown in the gas cutting apparatus 1 in Figures 1 to 3, is equipped with multiple torches, and multiple pipes are connected to each torch to supply fuel gas and oxygen gas. In Figure 4, for ease of understanding, only the piping 101 connected to one nozzle 332 is schematically shown. Also, in Figure 4, some components other than the characteristic configuration of this disclosure (e.g., safety devices, etc.) are omitted from the illustration.

[0030] The example shown in Figure 4 is a piping system when cutting is performed using 100% hydrogen gas. The flame formed by the combustion of 100% hydrogen gas does not form a visible white core. Therefore, a combustible mixed gas can be used instead of 100% hydrogen gas during the flame adjustment stage before cutting. Referring to Figure 4, a combustible mixed gas cylinder 111 (specifically, for example, "Hydrocut®" manufactured by Iwatani Gas Co., Ltd.) as a combustible mixed gas supply source, a hydrogen gas cylinder 112 as a hydrogen gas supply source, and an oxygen gas cylinder 113 as an oxygen gas supply source are connected to the gas cutting device. The three types of gases, combustible mixed gas, hydrogen gas, and oxygen gas, are switched as needed and supplied to the nozzle 332. In particular, the combustible mixed gas and hydrogen gas are switched selectively and supplied to the nozzle 332. The combustible mixed gas cylinder 111 is connected to piping 131 as the first pipe. The hydrogen gas cylinder 112 is connected to piping 132, which serves as a second pipe. Piping 131 and 132 are connected to piping 152, which serves as a fuel gas supply pipe, via a three-way valve 121.

[0031] Referring to Figure 4, solenoid valves 161 and 171, a mass flow controller 141, and a pressure gauge are installed in the middle of piping 131. The mass flow controller 141 may not be installed. Solenoid valves 162 and 172, a mass flow controller 142, and a pressure gauge are installed in the middle of piping 132. Piping 133 branches into combustion oxygen piping 153 and cutting oxygen piping 154. Solenoid valve 173 is installed in the middle of piping 133. Solenoid valve 163, a mass flow controller 143, and a pressure gauge are installed in the middle of combustion oxygen piping 153. Solenoid valve 164 and a pressure gauge are installed in the middle of cutting oxygen piping 154.

[0032] The three-way valve 121 selectively switches between a state in which pipe 131 and pipe 152 are connected, and a state in which pipe 132 and pipe 152 are connected. In other words, by switching the three-way valve 121, it is possible to selectively switch between a state in which a combustible mixed gas is supplied to the nozzle 332, and a state in which hydrogen gas is supplied to the nozzle 332.

[0033] The oxygen gas cylinder 113 is connected to pipe 133, which serves as an oxygen gas supply pipe. Pipe 133 branches into pipe 153, which supplies oxygen gas for preheating, and pipe 154, which supplies oxygen gas for cutting. Both pipes 153 and 154 are connected to the torch nozzle 332.

[0034] The combustible mixed gas cylinder 111 contains a combustible mixed gas. The combustible mixed gas used is one that can form a visible white core. The combustible mixed gas is typically hydrogen gas containing hydrocarbon gases such as ethylene gas and propylene gas. Specifically, for example, the combustible mixed gas preferably contains 4.5% to 12% by volume of ethylene, with the remainder being hydrogen gas and unavoidable impurities. The ethylene content in the combustible mixed gas is more preferably 4.5% to 10% by volume, and even more preferably 4.5% to 5.5% by volume. Specifically, for example, Iwatani Gas Co., Ltd.'s "Hydrocut (registered trademark)" can be used as the combustible mixed gas. When a combustible mixed gas with this configuration is used as the combustible mixed gas, a visible white core can be formed by mixing the combustible mixed gas with oxygen gas and burning it. Furthermore, a white core of the appropriate size can be formed with an oxygen flow rate equivalent to that used when forming a preheating flame with 100% hydrogen gas. This makes it easy to perform a series of steps: forming the white core to adjust the height of the nozzle, then switching the three-way valve to form a preheating flame with 100% hydrogen gas, and finally performing the cutting.

[0035] Hydrogen gas is contained in hydrogen gas cylinder 112. A commonly used hydrogen gas cylinder may be used, or other hydrogen gas containers may be used. Oxygen gas is contained in oxygen gas cylinder 113. A commonly used oxygen gas cylinder may be used, or other oxygen gas containers may be used. Other gas containers besides gas cylinders may include liquefied gas containers such as LGCs (Liquid Gas Containers) and CEs (Cold Evaporators), and can be selected according to the scale of the equipment and the amount of gas used.

[0036] The functions of the gas cutting device according to this disclosure will be explained assuming that the gas cutting device 1 shown in Figures 1 to 3 is equipped with the piping 101 shown in Figure 4. When cutting is performed, hydrogen gas is monitored by a sensor 81 provided in the hood 50. If hydrogen gas leaks from any point in the piping 101, the leaked hydrogen gas rises and reaches the cylindrical portion 52 of the hood 50. When the hydrogen gas reaches a predetermined concentration or higher, it is detected by the sensor 81. When the sensor 81 detects hydrogen gas, the solenoid valve that is open at that time among the solenoid valves provided in the piping 101 is closed, and the supply of flammable mixed gas, hydrogen gas, and oxygen gas is stopped. In other words, the gas flowing through the pipes 131, 132, and 133 is stopped, preventing further gas leakage. In particular, when the sensor 81 detects hydrogen gas, the solenoid valve 162, which is the first opening / closing part on the piping 132 that is the hydrogen gas supply piping, is closed, and hydrogen gas is not supplied to the torch 30. When sensor 81 detects hydrogen gas, not only solenoid valve 162 but also solenoid valves 163 and 164 can be closed, stopping the supply of oxygen gas.

[0037] The gas cutting apparatus according to this disclosure is not limited to one that uses 100% hydrogen gas, as shown in the example in Figure 4. A combustible mixed gas containing hydrogen can also be used as the fuel gas. When a combustible mixed gas containing hydrogen is used as the fuel gas, the gases connected to the gas cutting apparatus will consist of two types: the combustible mixed gas containing hydrogen and oxygen gas, and the three-way valve 121 and piping 132 shown in Figure 4 may not be required. In other words, a gas cutting apparatus that uses two types of gases, a combustible mixed gas containing hydrogen and oxygen gas, is also included in the gas cutting apparatus according to this disclosure.

[0038] (Operation flow of a gas cutting device) Figures 5-7 are flowcharts illustrating the steps involved in cutting steel materials using a gas cutting apparatus according to this disclosure, which utilizes a flammable mixed gas containing hydrogen and oxygen gas. Figure 5 shows the operation up to the start of cutting, Figure 6 shows the operation when the hydrogen sensor detects hydrogen, and Figure 7 shows the operation at the end of cutting. Figure 8 is a schematic diagram showing the piping system of the gas cutting apparatus in which the gas cutting procedures shown in Figures 5-7 are performed.

[0039] Referring to Figure 8, the piping 201 of the gas cutting device includes a combustible mixed gas cylinder 211, which is the fuel gas (specifically, for example, "Hydrocut®" manufactured by Iwatani Gas Co., Ltd.), and an oxygen gas cylinder 213 as an oxygen gas supply source. The combustible mixed gas and oxygen gas are supplied to the nozzle 232. The combustible mixed gas cylinder 211 is connected to piping 231, which is the first pipe. The oxygen gas cylinder 213 is connected to piping 233, which is the oxygen gas supply piping. Piping 233 branches into piping 253, which is the piping for supplying preheating oxygen gas, and piping 254, which is the piping for supplying cutting oxygen gas. Both piping 253 and 254 are connected to the nozzle 232.

[0040] A main valve 271, a solenoid valve 261, and a mass flow controller 241 are installed in the piping 231 of the flammable mixed gas cylinder 211. The piping 233 of the oxygen gas cylinder 213 is equipped with a main valve 273. A solenoid valve 263 and a mass flow controller 243 are installed in the piping 253, which supplies oxygen gas for preheating. A solenoid valve 264 is installed in the piping 254, which supplies oxygen gas for cutting. The following explanation will correspond to the case where piping 201 is installed in the gas cutting device 1 shown in Figures 1 to 3.

[0041] Referring to Figure 5, the operation up to the start of cutting will be explained. First, the device is prepared (S10). Specifically, the combustible mixed gas cylinder 211, which is the fuel gas, and the oxygen gas cylinder 213 are connected to the gas cutting device 1. After confirming that the connections are correct, the main valve 271 connected to the combustible mixed gas cylinder 211 and the main valve 273 connected to the oxygen gas cylinder 213 are opened. At this time, the torch fuel valve (solenoid valve 261) is closed, and the solenoid valve 72 provided in the hood 50 is open. The hydrogen sensor (sensor 81) provided in the hood 50 is OFF. Next, the ignition device is prepared. The steel material S to be cut is set on the surface plate 61.

[0042] Next, the torch fuel valve is opened (S11), and the fuel gas is ignited using the ignition device (S12). After ignition is confirmed, the oxygen valve (solenoid valve 263) is opened to adjust the flame. Specifically, the length of the white core formed in the flame is adjusted. The length of the white core is not particularly limited, but for example, when cutting steel plates with a thickness of about 20 mm to 200 mm, it is preferable to form a flame with a white core length of about 2 mm to 6 mm. The height of the nozzle 232 is adjusted based on the white core.

[0043] After a suitable flame has been formed, the hydrogen sensor is turned ON (S14). Also, the solenoid valve provided in the hood is closed (S15). These steps may be performed substantially simultaneously, or in reverse order.

[0044] After confirming that the hydrogen sensor is ON and the hood solenoid valve is closed, the portion of the steel to be cut is heated (preheated) by the flame formed in step S13 (S16). The steel is heated by the preheating flame. Step S16 is the preheating process. Once preheating is performed and the steel reaches its combustion temperature, the cutting oxygen valve (solenoid valve 264 on the cutting oxygen supply pipe 254) is opened (S17). Cutting oxygen gas is injected from the nozzle, and this oxygen gas is blown onto the portion of the heated steel to be cut. As a result, the steel in that portion burns and melts. Furthermore, the molten steel is removed by blowing oxygen gas injected from the nozzle. The steel is cut by moving the nozzle along the predetermined cutting shape at a predetermined cutting speed (S18). During steps S15 to S18, the hydrogen sensor is ON and monitoring the hydrogen collected in the hood. The hydrogen sensor's detection concentration is set according to the usage conditions, etc. The hydrogen sensor's detection concentration is set to a value obtained by multiplying the lower limit of the explosive hydrogen concentration range in air (4.0%) by a sufficient safety factor.

[0045] Figure 6 is a flowchart showing the operation of the gas cutting device when the hydrogen sensor detects hydrogen. The hydrogen sensor detects hydrogen (S21). The hydrogen sensor sends a closing signal to the solenoid valve (solenoid valve 261) on the supply piping for the flammable mixed gas, which is the fuel gas, and to the solenoid valves (solenoid valves 263, 264) on the oxygen supply piping (S22). Upon receiving this signal, the solenoid valves on the supply piping for the flammable mixed gas and the solenoid valves on the oxygen supply piping are closed (S23). In addition, the travel operation of the gas cutting device is emergency stopped (S24). Through these steps, if a hydrogen leak is detected, the gas supply can be stopped immediately, preventing further leaks and ensuring safety. In addition, the travel operation of the gas cutting device can be stopped.

[0046] After the gas cutting device has stopped operating, the cause of the detected hydrogen is checked (S25). Specifically, for example, the leak location can be checked using soapy water. The check can be performed by a human, or it can be performed mechanically or automatically using sensors, etc. If the cause cannot be identified, the check for the cause is repeated (NO in S25). This operation is repeated until the cause is eliminated. Once the cause is identified (YES in S25), the emergency stop of the gas cutting device is released (S26). The solenoid valve of the hood exhaust port is also opened (S27). This operation releases the hydrogen accumulated in the hood (S28). The hydrogen accumulated in the hood may also be released through the exhaust line. The hydrogen sensor is also turned OFF (S29). After these operations, the process returns to S11 (Figure 5).

[0047] Figure 7 is a flowchart showing the operation of the gas cutting device at the end of cutting. When the predetermined cutting operation is completed, the solenoid valve (solenoid valve 264) on the oxygen supply piping for cutting is closed (S31). Next, the solenoid valve (solenoid valve 263) on the oxygen supply piping is closed (S32). Next, the fuel gas solenoid valve (solenoid valve 261) is closed (S33). The fire is extinguished because the supply of fuel gas has stopped. Next, the operation of the gas cutting device is stopped (S34). Next, the solenoid valve (solenoid valve 72) at the hood exhaust port is opened (S35). The gas accumulated in the hood is released. Also, the hydrogen sensor is turned OFF (S36). After it is confirmed that the fire has been extinguished and the operation of the gas cutting device has stopped, the cut steel materials placed on the surface plate are arranged (S37). This operation is performed by a human. If cutting is to be continued, a new steel material to be cut is placed on the surface plate (S39). When cutting is finished, close the main valves for fuel gas and oxygen (valves 271 and 273) (S38).

[0048] Note that the above steps are not limited to being performed mechanically and automatically; some may be performed by a human. Also, some steps can be rearranged or performed simultaneously. In the case where 100% hydrogen gas is used as the fuel gas, as in the example in Figure 4, in the preparation step of the apparatus (S10), a flame of the combustible mixed gas supplied from the combustible mixed gas cylinder (111) is formed, and the height of the nozzle is adjusted using a flame in which the white core is visible. After adjusting the height of the nozzle, the three-way valve (121) is switched so that 100% hydrogen gas (Figure 4, 112) is supplied to the nozzle as the fuel gas.

[0049] The embodiments disclosed herein should be understood in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of Symbols]

[0050] 1 Gas cutting device, 10 Traveling section, 11 Base, 12 Rail, 20 Main body, 21 Support base, 22 Leg section, 23 Traverse rail, 24 Carriage, 28 End face cover, 30 Torch, 31 Blowpipe, 32, 232, 332 Nozzle, 33 Holder, 34 Up / Down device, 40 Hose cover, 41 Piping cover, 42 Gas control box, 50 Hood, 51 Roof section, 52 Cylindrical section, 53 Support column, 55 Roof surface, 56 Skirt section, 60 Mounting section, 61 Surface plate, 72, 161, 162, 163, 164, 171, 172, 173, 261, 262, 263 Solenoid valve, 75 Drive device, 81 Sensors, 101, 131, 132, 133, 152, 153, 154, 201, 231, 233, 254 Piping, 111, 211 Flammable mixed gas cylinder, 112 Hydrogen gas cylinder, 113, 313 Oxygen gas cylinder, 121 Three-way valve, 141, 142, 143, 241, 242, 243 Mass flow controller, 271, 273 Main valve.

Claims

1. A first rail extending in the first direction, It comprises a main body that can travel on the first rail, The main body is, A support base extending in a direction intersecting the first direction, A torch supported on the support base and movable along the support base, A fuel gas pipe connected to the torch, A hood fixed to the support base and covering the top of the support base, Includes, The aforementioned fuel gas piping is The torch is equipped with a first opening / closing unit that switches between a state in which fuel gas is supplied to the torch and a state in which fuel gas is not supplied to the torch. The aforementioned hood is A second opening / closing section is provided at a position higher than the roof surface of the aforementioned hood, The device includes a sensor for detecting hydrogen gas, which is located below the second opening / closing section. When the sensor detects hydrogen gas, the first opening / closing section is closed, and fuel gas is not supplied to the torch. Gas cutting device.

2. When the sensor detects hydrogen gas, the second opening / closing section is opened. The gas cutting apparatus according to claim 1.

3. The first rail includes a pair of rails that are parallel to each other. Each of the ends of the support base is supported by each of the pair of rails. A gas cutting apparatus according to claim 1 or claim 2.

4. The aforementioned hood is The roof surface includes a sloping section that is inclined to become higher towards the center, The roof surface includes a cylindrical portion that protrudes upward from the uppermost part of the roof surface, The second opening / closing part and the sensor are arranged inside the cylindrical part. A gas cutting apparatus according to claim 1 or claim 2.

5. The support base and the hood are provided with a plurality of support columns extending upward from the support base, The hood is supported by a plurality of the aforementioned support columns. A gas cutting apparatus according to claim 1 or claim 2.

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