JP2024085619A - Gas cutting device - Google Patents

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

This disclosure relates to a gas cutting device.

Gas cutting devices equipped with a mechanism for detecting gas leakage are known. This type of technology is described, for example, in Patent Document 1. Patent Document 1 describes that in a gas cutting device, a gas supply pipe is provided with multiple on-off valves and a sensor. In the gas cutting device of Patent Document 1, a sensor that detects the flow of gas is placed in a section of the gas supply pipe partitioned by the on-off valve. The presence or absence of a gas leak is determined by comparing the on-off condition of the on-off valve with the signal output from the sensor. In other words, if it is detected that gas is flowing when gas should not be flowing, it is determined that gas is leaking from the pipe.

Patent Document 2 discloses a gas detection device that detects gas leakage from equipment installed in a valve stand for liquefied natural gas (LNG). The gas detection device of Patent Document 2 is installed on the top of the valve stand. The gas detection device of Patent Document 2 includes a hood with a guide plate, a suction fan that sucks in the detected gas captured by the hood, and a sensor.

Japanese Patent Application Laid-Open No. 7-100642 JP 2006-90891 A

In Patent Document 1, a sensor is placed in a specific section of the gas supply pipe, but it would be preferable to be able to detect gas leaks over a wider area, not just in a specific section. In addition, 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 it to devices such as gas cutting devices where the pipes and nozzle move while operating.

One of the objectives of the present disclosure is to provide a gas cutting device that uses a gas containing hydrogen as a fuel gas and is capable of detecting hydrogen gas leaks, thereby providing a highly safe gas cutting device.

The gas cutting device according to the present disclosure comprises a first rail extending in a first direction and a main body capable of running on the first rail. The main body includes a support base extending in a direction intersecting the first direction, a torch supported by the support base and movable on the support base 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 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 hood includes a second opening/closing unit provided at a position higher than the roof surface of the hood, and a sensor that is disposed below the second opening/closing unit and detects hydrogen gas. When the sensor detects hydrogen gas, the first opening/closing unit is closed, and the state in which fuel gas is not supplied to the torch is established.

According to the present disclosure, it is possible to provide a gas cutting device that uses a gas containing hydrogen and is capable of detecting hydrogen gas leaks, thereby making the gas cutting device highly safe.

FIG. 1 is a perspective view of a gas cutting device according to an embodiment. FIG. 2 is a plan view showing a main body of the gas cutting device according to the embodiment. FIG. 3 is a cross-sectional perspective view of a hood of the gas cutting device according to the embodiment. FIG. 4 is a schematic diagram showing a piping system of the gas cutting device according to the embodiment. FIG. 5 is a flowchart showing the operation of the gas cutting device according to the embodiment. FIG. 6 is a flowchart showing the operation of the gas cutting device according to the embodiment. FIG. 7 is a flowchart showing the operation of the gas cutting device according to the embodiment. FIG. 8 is a schematic diagram showing a piping system of the gas cutting device according to the embodiment.

[Outline of the embodiment]
First, embodiments of the cutting device according to the present disclosure will be listed and described.
The gas cutting device according to the present disclosure includes a first rail extending in a first direction and a main body section capable of traveling on the first rail. The main body section includes a support base extending in a direction intersecting the first direction, a torch supported by the support base and movable on the support base 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 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 hood includes a second opening/closing unit provided at a position higher than the roof surface of the hood, and a sensor disposed below the second opening/closing unit for detecting hydrogen gas. When the sensor detects hydrogen gas, the first opening/closing unit is closed, and the state in which fuel gas is not supplied to the torch is established.

In order to meet the need to reduce _CO2 emissions, the use of hydrogen gas as a fuel gas in gas cutting of steel materials is being considered. Hydrogen has the characteristics of having a lower gas density and a wider explosion range in air than other fuel gases. For this reason, it is desirable for a gas cutting device that uses hydrogen gas to maintain safety even in the unlikely event of a hydrogen gas leak. Therefore, a gas cutting device equipped with a mechanism for detecting hydrogen gas leaks has been considered. Then, a configuration has been found in which a hood is provided above a support base that supports a reciprocating torch, and a sensor that detects hydrogen gas is provided on the top of the hood in the gas cutting device. Furthermore, a configuration has been found in which the supply of hydrogen gas is stopped when the sensor detects hydrogen gas.

The gas cutting device according to the present disclosure includes a rail extending in the direction of a first axis (X axis), and a torch supported on a support base supported on the rail and reciprocating along a second axis (Y axis) intersecting the first axis. The gas cutting device according to the present disclosure is provided with a hood covering the upper part of the support base, so that even in a gas cutting device that moves in the X-Y axis direction, hydrogen gas leaking from the vicinity of the torch or from a pipe connected to the torch can be detected without providing a large-scale mechanism that covers the entire range of movement. Hydrogen gas rises quickly in the air due to its low density. Therefore, leaked hydrogen gas reaches the hood in a short time and can 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, the leak can be quickly detected and stopped. Thus, according to the gas cutting device according to the present disclosure, a gas cutting device that can detect hydrogen gas leakage and is highly safe can be provided.

In the gas cutting device, when the sensor detects hydrogen gas, the second opening/closing section can be opened. The second opening/closing section is provided on the hood and is located at a position higher than the roof surface of the hood. By opening the second opening/closing section in this position, the hydrogen gas captured in the hood can be released from inside the hood to the outside. With this configuration, it is possible to prevent the captured hydrogen from leaking and remaining in the hood and becoming highly concentrated, further ensuring safety.

In the gas cutting device, the first rail can include a pair of rails that are parallel to each other, and both ends of the support table can be supported by each of the pair of rails. With this configuration, even in a so-called gate-type large gas cutting device in which the support table is supported by a pair of rails, it is possible to safely cut steel material using fuel gas containing hydrogen gas.

In the gas cutting device, the hood includes a roof surface including an inclined portion that is inclined so as to become higher toward the center, and a tubular portion that protrudes upward from the top of the roof surface, and the second opening/closing portion and the sensor are disposed inside the tubular portion. With this configuration, hydrogen gas can be efficiently collected in the hood, and in the event of a leak, the hydrogen gas can be quickly detected and the collected hydrogen gas can be discharged from the top of the hood.

The gas cutting device may include a plurality of supports extending upward from the support stand between the support stand and the hood, and the hood may be supported by the plurality of supports. This configuration provides a gas cutting device that is highly safe even when using hydrogen gas, without compromising the operational efficiency of conventional gas cutting devices. In addition, the hood can be easily attached and detached depending on the mode of use of the gas cutting device and the needs.

[Specific Example of the Embodiment]
Next, a specific embodiment of the gas cutting device according to the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are given the same reference numerals, and the description thereof will not be repeated. In this specification, "hydrogen gas" means a gas consisting of hydrogen and inevitable impurities. In this specification, hydrogen gas that is not a mixed gas may be referred to as 100% hydrogen gas in order to distinguish it from a mixed gas. However, 100% hydrogen gas does not mean a gas consisting of 100% hydrogen in a mathematically strict sense, and generally includes gases that are commercially available as hydrogen gas.

(Configuration of gas cutting device)
Fig. 1 is a perspective view showing an entire gas cutting device 1 according to the present disclosure. With reference to Fig. 1, the gas cutting device 1 includes a running section 10, a main body section 20, and a mounting section 60. In Fig. 1, the direction in which the running section 10 extends is indicated as the X-axis direction, the width direction of the main body section 20 is indicated as the Y-axis direction, and the height direction of the gas cutting device 1 is indicated as the Z-axis direction. In the following description, these axial directions are used as references. In addition, in the following description, "upward" refers to the positive direction of the Z axis, and "downward" refers to the negative direction of the Z axis.

Referring to FIG. 1, the running unit 10 includes a base 11 and a rail 12 as a first rail fixed to the upper surface of the base 11. A main body 20 is provided on the rail 12. The main body 20 can run back and forth on the rail 12 along the X-axis direction. The main body 20 includes a support table 21, a plurality of torches 30 that can move back and forth on the support table 21 along the width direction (Y-axis direction) of the main body 20, and a hood 50 that covers the upper part of the support table 21. The gas cutting device 1 can cut the steel material S placed on the placement unit 60 by moving the torches 30 in the X-Y directions.

The running section 10 includes a pair of bases 11 and a pair of rails 12 that are installed parallel to each other. The main body section 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 section 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, that is, in a direction that intersects with the rails 12. The support base 21 extends in a direction perpendicular to the rails 12.

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 has a traverse rail 23. A plurality of carriages 24 are arranged on the traverse rail 23. The carriages 24 are reciprocated along the traverse rail 23 by a drive device 75. In Figure 2, only a part of the drive device 75 is shown. A torch 30 is mounted on each of the carriages 24. The torch 30 has a blowpipe 31 and a burner 32 attached to the tip of the blowpipe 31. The blowpipe 31 is held by a holder 33. The holder 33 is connected to a lifting device 34. A plurality of hoses (not shown) as fuel gas piping and oxygen gas piping are connected to the blowpipe 31 via joints. The hoses connected to each of the torches 30 are housed in a hose cover 40. The hoses are connected to fuel gas piping and oxygen gas piping housed inside a piping cover 41 (Figure 1). The fuel gas pipe and the oxygen gas pipe in the pipe cover 41 are each provided with an electromagnetic valve. The fuel gas pipe and the oxygen gas pipe are each connected to a joint pipe provided in the gas control box 42. The fuel gas pipe in the gas control box 42 is provided with an electromagnetic valve as a first opening and closing unit. The oxygen gas pipe in the gas control box 42 is also provided with an electromagnetic valve. By opening and closing the electromagnetic valve provided in the fuel gas pipe, 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 are switched. In the gas cutting apparatus 1, when a sensor 81 (FIG. 3) provided in the hood 50 detects hydrogen, the electromagnetic valve provided in the control box 42 is closed.

1 and 2, a hood 50 is fixed to the support base 21, spaced apart from the support base 21 and covering the upper part of the support base 21. The hood 50 includes a roof portion 51, a cylindrical portion 52 as a tube portion, and a support 53. When the roof portion 51 is viewed planarly in the height direction (Z-axis direction), it has a rectangular shape. The dimension of the roof portion 51 along the width direction (Y-axis direction) is approximately the same as the width direction dimension of the support base 21. The dimension of the roof portion 51 along the depth direction (X-axis direction) is the dimension covering the range from the torch 30 to the piping cover 41, that is, the range above where the torch and piping are located. That is, the roof portion 51 is positioned so as to cover the torch 30, the hose connected to the torch 30, and the piping connected to the hose. Note that, as shown in FIG. 2, when the torch 30 is located near the end of the lateral rail 23, a part of the hose cover 40 may be located outside the range covered by the roof portion 51.

The pillars 53 are fixed to the support base 21. Specifically, the pillars 53 on both ends of the roof 51 are fixed to the end covers 28 of the support base 21. The pillars 53 on the rear side of the roof 51 are fixed to the rear of the support base 21. The pillars 53 are not limited to being directly attached to the support base 21, but may be fixed to the support base 21 via a bracket, an extension member, or the like. The pillars 53 may also include a height adjustment mechanism. The height of the hood 50 can be set according to the size of the entire device and other configurations, and is not particularly limited as long as the effect of hydrogen detection is obtained. For example, the lower end of the roof 51 may be set to a height 1000 to 1500 mm above the position of the traverse rail 23.

3 is a cross-sectional perspective view of the upper part of the hood 50. Referring to FIGS. 2 and 3, the roof part 51 of the hood 50 includes a roof surface 55 that is generally inclined so as to become higher toward the center, and a skirt part 56 that hangs down from the outer edge of the roof surface 55. A cylindrical part 52 that protrudes upward from the roof surface 55 is provided in the center of the roof surface 55. Inside the cylindrical part 52, an electromagnetic valve 72 as a second opening/closing part and a sensor 81 that detects hydrogen gas are provided. The sensor 81 is installed below the electromagnetic valve 72. The opening and closing of the electromagnetic valve 72 switches the opening and closing of the cylindrical part 52. The tip of the cylindrical part 52 may be open to the atmosphere, or an exhaust pipe may be connected to it. The cylindrical part 52 is an exhaust port of the hood 50. In the hood 50, the electromagnetic valve 72 is provided at a position higher than the roof surface 55. The electromagnetic valve 72 can be provided at the tip of the cylindrical part 52. A tube for connecting an exhaust pipe may also be provided above the solenoid valve 72. The solenoid valve 72 is closed while gas cutting is being performed without any abnormalities, and is opened when the sensor 81 detects hydrogen gas. When the solenoid valve 72 is opened, hydrogen gas remaining in the roof portion 51 is exhausted from the hood 50. Naturally, not only hydrogen gas but also various gases lighter than air are exhausted in the same manner. Forced exhaust can also be performed using an exhaust device or fan.

The shape of the roof surface 55 is not limited to the form 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 that does not have an incline, or the roof surface may include a curved surface. A groove for guiding gas may be formed in part of the roof surface. The cylindrical portion 52 is not limited to being provided in the center of the roof portion. Taking into consideration the gas flow and wiring, it may be provided in a position other than the center. The cylindrical portion 52 may be a tube with a rectangular cross section, and may be provided with a large diameter portion that serves as a gas retention portion.

The gas cutting device 1 may also be provided with a sensor for detecting hydrogen gas in addition to the sensor 81 provided in the hood 50. For example, a hydrogen gas detection sensor can be provided near the gas supply source cylinder connected to the gas cutting device 1, or near the connection point connecting the cylinder to the main body 20 (for example, inside the gas control box 42).

In Figures 1 to 3, a gate-type CNC cutting device is shown as the gas cutting device 1, but the gas cutting device according to the present disclosure is not limited to this. For example, it may be a frame planer, a pattern copy cutting machine, etc.

(Fuel gas for use in gas cutting equipment)
In the gas cutting device 1, a gas containing hydrogen is used as the fuel gas. The gas containing hydrogen may be 100% hydrogen gas or a mixed gas containing hydrogen. The gas mixed with hydrogen is not particularly limited as long as the required combustion performance can be obtained, but typically includes 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, as the fuel gas used in the gas cutting device according to the present disclosure, in addition to 100% hydrogen gas, a mixed gas containing 2 to 12 volume % ethylene relative to hydrogen gas (for example, "Hydrocut (registered trademark)" manufactured by Iwatani Industrial Gas Corporation, etc.) can be used.

(Gas cutting device piping)
Fig. 4 is a schematic system diagram showing piping 101 in a gas cutting apparatus according to the present disclosure. The gas cutting apparatus according to the present disclosure is provided with a plurality of torches, as in the gas cutting apparatus 1 shown in Figs. 1 to 3, and a plurality of pipes for supplying fuel gas and oxygen gas are connected to each of the torches. For ease of understanding, Fig. 4 shows only the pipe 101 connected to one nozzle 332 in a schematic manner. Also, in Fig. 4, some configurations other than the characteristic configuration according to the present disclosure (e.g., a safety device, etc.) are omitted from the illustration.

The example shown in FIG. 4 is a piping system when cutting is performed using 100% hydrogen gas. The flame formed by burning 100% hydrogen gas does not form a visible white core. Therefore, in the stage of adjusting the flame before cutting, a flammable mixed gas can be used instead of 100% hydrogen gas. With reference to FIG. 4, a flammable mixed gas (specifically, for example, "Hydrocut (registered trademark)" manufactured by Iwatani Industrial Gas Co., Ltd.) cylinder 111 as a flammable 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. Three types of gas, flammable mixed gas, hydrogen gas, and oxygen gas, are switched as necessary and supplied to the nozzle 332. In particular, the flammable mixed gas and hydrogen gas are switched alternatively and supplied to the nozzle 332. The flammable mixed gas cylinder 111 is connected to a pipe 131 as a first pipe. The hydrogen gas cylinder 112 is connected to a pipe 132 as a second pipe. Pipes 131 and 132 are connected to a pipe 152 as a fuel gas supply pipe via a three-way valve 121.

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

The three-way valve 121 selectively switches between a state in which the pipes 131 and 152 are in communication with each other and a state in which the pipes 132 and 152 are in communication with each other. In other words, by switching the three-way valve 121, it is possible to selectively switch between a state in which the combustible mixed gas is supplied to the burner 332 and a state in which hydrogen gas is supplied to the burner 332.

The oxygen gas cylinder 113 is connected to a pipe 133 that serves as an oxygen gas supply pipe. The pipe 133 branches into a pipe 153 that supplies oxygen gas for preheating, and a pipe 154 that supplies oxygen gas for cutting. Both pipes 153 and 154 are connected to a nozzle 332.

The combustible mixed gas cylinder 111 contains a combustible mixed gas. As the combustible mixed gas, a gas capable of forming a visible white core is used. The combustible mixed gas is typically hydrogen gas containing a hydrocarbon gas such as ethylene gas or propylene gas. Specifically, for example, the combustible mixed gas preferably contains 4.5 volume % to 12 volume % ethylene, with the remainder being hydrogen gas and unavoidable impurities. The ethylene content in the combustible mixed gas is more preferably 4.5 volume % to 10 volume %, and even more preferably 4.5 volume % to 5.5 volume %. Specifically, for example, "Hydrocut (registered trademark)" manufactured by Iwatani Gas Corporation can be used as the combustible mixed gas. When a combustible mixed gas of this composition 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. In addition, a white core of appropriate size can be formed with the same oxygen flow rate as when forming a preheating flame with 100% hydrogen gas. This facilitates the entire process of forming a white core, adjusting the height of the nozzle, and then switching the three-way valve to form a preheating flame with 100% hydrogen gas and perform cutting.

Hydrogen gas cylinder 112 contains hydrogen gas. The hydrogen gas cylinder may be a cylinder filled with commonly used hydrogen gas, or may be any other hydrogen gas storage container. Oxygen gas cylinder 113 contains oxygen gas. The oxygen gas cylinder may be a cylinder filled with commonly used oxygen gas, or may be any other oxygen gas storage container. Gas storage containers other than gas cylinders may be liquefied gas containers such as LGCs (Liquid Gas Containers) and CEs (Cold Evaporators), and can be selected according to the size of the facility and the amount of gas used.

The function of the gas cutting device according to the present disclosure will be described assuming that the gas cutting device 1 shown in FIGS. 1 to 3 is equipped with the piping 101 shown in FIG. 4. When cutting is performed, hydrogen gas is monitored by a sensor 81 provided in the hood 50. If hydrogen gas leaks from any location 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 valves that are open at that time among the solenoid valves provided in the piping 101 are closed, and the supply of the flammable mixed gas, hydrogen gas, and oxygen gas is stopped. In other words, the gas flowing through the piping 131, 132, and 133 is stopped, and further gas leakage can be prevented. In particular, when the sensor 81 detects hydrogen gas, the solenoid valve 162 as the first opening and closing part on the piping 132, which is the hydrogen gas supply piping, is closed, and hydrogen gas is not supplied to the torch 30. When the sensor 81 detects hydrogen gas, not only the solenoid valve 162 but also the solenoid valves 163 and 164 are closed, and the supply of oxygen gas is also stopped.

The gas cutting device according to the present disclosure is not limited to one that uses 100% hydrogen gas as in the example of FIG. 4. A flammable mixed gas containing hydrogen can also be used as the fuel gas. When a flammable mixed gas containing hydrogen is used as the fuel gas, the gases connected to the gas cutting device are two types, a flammable mixed gas containing hydrogen and oxygen gas, and the three-way valve 121 and piping 132 shown in FIG. 4 do not need to be provided. In other words, a gas cutting device that uses two types of gas, a flammable mixed gas containing hydrogen and oxygen gas, is also included in the gas cutting device according to the present disclosure.

(Operation flow of gas cutting device)
Figures 5 to 7 are flow charts showing steps for cutting steel using a flammable mixed gas containing hydrogen and oxygen gas in the gas cutting apparatus according to the present disclosure. 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 to 7 are performed.

Referring to FIG. 8, the piping 201 of the gas cutting device includes a cylinder 211 of a flammable mixed gas (specifically, for example, "Hydrocut (registered trademark)" manufactured by Iwatani Industrial Gases Corporation) which is a fuel gas, and an oxygen gas cylinder 213 as an oxygen gas supply source. The flammable mixed gas and oxygen gas are supplied to the flame nozzle 232. The flammable mixed gas cylinder 211 is connected to a pipe 231 which is a first pipe. The oxygen gas cylinder 213 is connected to a pipe 233 which is an oxygen gas supply pipe. The pipe 233 branches into a pipe 253 which is a pipe which supplies oxygen gas for preheating, and a pipe 254 which is a pipe which supplies oxygen gas for cutting. Both pipes 253 and 254 are connected to the flame nozzle 232.

A main valve 271, a solenoid valve 261, and a mass flow controller 241 are provided in the piping 231 of the flammable mixed gas cylinder 211. A main valve 273 is provided in the piping 233 of the oxygen gas cylinder 213. A solenoid valve 263 and a mass flow controller 243 are provided in the piping 253, which is the piping for supplying preheating oxygen gas. A solenoid valve 264 is provided in the piping 254, which is the piping for supplying cutting oxygen gas. The following will be described in relation to the case where the piping 201 is provided in the gas cutting device 1 shown in Figures 1 to 3.

The operation up to the start of cutting will be described with reference to FIG. 5. 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 they are connected correctly, 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. In addition, an ignition device is prepared. The steel material S to be cut is set on the base plate 61.

Then, 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 and the flame is adjusted. Specifically, the length of the white core formed in the flame is adjusted. There is no particular limit to the length of the white core, but when attempting to cut a steel plate with a thickness of about 20 mm to 200 mm, for example, it is preferable that a flame with a white core length of about 2 mm to 6 mm is formed. The height of the nozzle 232 is adjusted based on the white core.

After an appropriate flame is 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 the order may be reversed.

After it is confirmed 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. When the preheating is performed and the combustion temperature of the steel is reached, the cutting oxygen valve (solenoid valve 264 on the cutting oxygen supply pipe 254) is opened (S17). Cutting oxygen gas is ejected from the nozzle, and the oxygen gas is sprayed onto the portion of the heated steel to be cut. This burns and melts the steel in that portion. The molten steel is then removed by the spraying of oxygen gas ejected from the nozzle. The nozzle is moved at a predetermined cutting speed along the predetermined cutting shape to cut the steel (S18). During steps S15 to S18, the hydrogen sensor is ON and monitors the hydrogen captured in the hood. The detection concentration of the hydrogen sensor is set according to the usage conditions, etc. The detection concentration of the hydrogen sensor is set to a value obtained by multiplying the lower limit of the explosive concentration range of hydrogen in air (4.0%) by a sufficient safety factor.

Figure 6 is a flow chart 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 close signal to the solenoid valve (solenoid valve 261) on the supply pipe of the flammable mixed gas, which is the fuel gas, and to the solenoid valves (solenoid valves 263, 264) on the oxygen supply pipe (S22). In response to this signal, the solenoid valve on the supply pipe of the flammable mixed gas and the solenoid valve on the oxygen supply pipe are closed (S23). In addition, the traveling operation of the gas cutting device is urgently stopped (S24). Through these steps, if a hydrogen leak is detected, the gas supply is quickly stopped, preventing further leaks and ensuring safety. In addition, the traveling of the gas cutting device can be stopped.

After the operation of the gas cutting device has been stopped, the cause of the detection of hydrogen is confirmed (S25). Specifically, for example, the location of the leak can be confirmed using soapy water or the like. The confirmation can be performed manually, mechanically, or automatically using a sensor or the like. If the cause cannot be confirmed, confirmation of the cause is repeated (NO in S25). This operation is repeated until the cause is removed. If the cause is confirmed (YES in S25), the emergency stop of the gas cutting device is released (S26). In addition, the solenoid valve of the hood exhaust port is opened (S27). This operation releases the hydrogen that has accumulated in the hood (S28). The hydrogen that has accumulated in the hood may be released through the exhaust line. In addition, the hydrogen sensor is turned OFF (S29). After these operations, the process returns to S11 (FIG. 5).

Figure 7 is a flow chart showing the operation of the gas cutting device at the end of cutting. When the specified cutting operation is completed, the solenoid valve (solenoid valve 264) on the oxygen supply pipe for cutting is closed (S31). Then, the solenoid valve (solenoid valve 263) on the oxygen supply pipe is closed (S32). Then, the fuel gas solenoid valve (solenoid valve 261) is closed (S33). The fire is extinguished because the supply of fuel gas has stopped. Then, the operation of the gas cutting device is stopped (S34). Then, the solenoid valve (solenoid valve 72) of the hood exhaust port is opened (S35). The gas remaining in the hood is released. In addition, 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 material placed on the surface plate is arranged (S37). This operation is performed by a human being. If cutting is to be continued, a new steel material to be cut is placed on the surface plate (S39). When cutting is to end, the main fuel gas and oxygen valves (valves 271, 273) are closed (S38).

The above steps are not limited to being performed mechanically or automatically, and may be partially performed by a human being. Some steps may be performed in a different order or simultaneously. When 100% hydrogen gas is used as the fuel gas as in the example of FIG. 4, in the device preparation step (S10), a flame of the flammable mixed gas supplied from the flammable mixed gas cylinder (111) is formed, and the flame with a visible white core is used to adjust the height of the nozzle. After adjusting the height of the nozzle, the three-way valve (121) is switched so that 100% hydrogen gas (FIG. 4, 112) is supplied to the nozzle as the fuel gas.

The embodiments disclosed herein are illustrative in all respects and should not be construed as limiting. The scope of the present invention is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope of the claims.

1 Gas cutting device, 10 Running part, 11 Base, 12 Rail, 20 Main body, 21 Support, 22 Leg, 23 Traverse rail, 24 Carriage, 28 End cover, 30 Torch, 31 Blowpipe, 32, 232, 332 Nozzle, 33 Holder, 34 Lifting device, 40 Hose cover, 41 Pipe cover, 42 Gas control box, 50 Hood, 51 Roof, 52 Cylinder, 53 Support, 55 Roof surface, 56 Skirt, 60 Placement part, 61 Surface plate, 72, 161, 162, 163, 164, 171, 172, 173, 261, 262, 263 Solenoid valve, 75 Drive device, 81 Sensor, 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 (5)

A first rail extending in a first direction;
a main body portion capable of running on the first rail,
The main body portion is
A support base extending in a direction intersecting the first direction;
a torch supported by the support base and movable on the support base along the support base;
A fuel gas pipe connected to the torch;
A hood fixed to the support base and covering an upper portion of the support base;
Including,
The fuel gas piping is
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 hood is
A second opening/closing portion provided at a position higher than a roof surface of the hood;
a sensor disposed below the second opening/closing portion and configured to detect hydrogen gas;
When the sensor detects hydrogen gas, the first opening/closing portion is closed, and no fuel gas is supplied to the torch. When the sensor detects hydrogen gas, the second opening and closing portion is opened.
2. The gas cutting device according to claim 1. The first rail includes a pair of rails that are parallel to one another;
Each of the ends of the support base is supported by each of the pair of rails.
3. The gas cutting device according to claim 1 or 2. The hood is
The roof surface includes an inclined portion that is inclined so as to become higher toward a center portion;
A tube portion protruding upward from the top of the roof surface,
The second opening/closing unit and the sensor are disposed inside the cylindrical portion.
3. The gas cutting device according to claim 1 or 2. a plurality of support columns extending upward from the support base between the support base and the hood;
The hood is supported by a plurality of the struts.
3. The gas cutting device according to claim 1 or 2.

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