Steel fusing device and steel fusing method

Abstract

To provide a steel material fusion-cutting device and a steel material fusion-cutting method which can perform gas fusion-cutting with 100% of hydrogen gas and easily adjust the burner height to a proper position.SOLUTION: A steel material fusion-cutting device comprises: an oxygen gas supply pipe which is connected with an oxygen gas supply source; a first pipe which is connected with a combustible mixed gas supply source; a second pipe which is connected with a hydrogen gas supply source; a combustion gas supply pipe which is connected with the first pipe and the second pipe via a switching mechanism; and a burner which is connected with the oxygen gas supply pipe and the combustion gas supply pipe. The switching mechanism can alternatively switch between the first state where the first pipe communicates to the combustion gas supply pipe and the second state where the second pipe communicates to the combustion gas supply pipe.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a steel fusing device and a steel fusing method. [Background technology]

[0002] It is known to use hydrogen gas in gas cutting of steel materials. This type of technology is described in, for example, Patent Document 1.

[0003] Patent Document 1 discloses a method for cutting a workpiece (steel material) using a combustion gas that is a mixture of hydrogen gas and a hydrocarbon gas, with the hydrocarbon gas content being more than 0% by volume and not more than 4% by volume. Conventionally, when attempting to use 100% hydrogen gas as the combustion gas, the white core formed at the tip of the nozzle cannot be seen, posing a challenge in adjusting the preheating flame. In response to this, Patent Document 1 discloses a cutting method that includes using a combustion gas with the above composition, using a nozzle with a specific shape, and adjusting the nozzle so that a specific point identified by the nozzle is aligned with the workpiece surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO2011 / 132496 Summary of the Invention [Problem to be solved by the invention]

[0005] The gas cutting method disclosed in Patent Document 1 uses hydrogen gas containing hydrocarbon gas as the combustion gas to make the core visible. However, due to demands for further reductions in CO2 emissions, there is a need for gas cutting using 100% hydrogen gas.

[0006] The object of the present disclosure is to provide a steel fusing device and a steel fusing method that are capable of gas cutting using 100% hydrogen gas and that allow the nozzle height to be easily adjusted to an appropriate position. [Means for solving the problem]

[0007] A steel fusing device according to the present disclosure includes an oxygen gas supply pipe connected to an oxygen gas supply source, a first pipe connected to a combustible mixed gas supply source, a second pipe connected to a hydrogen gas supply source, a combustion gas supply pipe to which the first pipe and the second pipe are connected via a switching mechanism, and a crater to which the oxygen gas supply pipe and the combustion gas supply pipe are respectively connected. The switching mechanism is capable of selectively switching between a first state in which the first pipe and the combustion gas supply pipe are connected to each other, and a second state in which the second pipe and the combustion gas supply pipe are connected to each other.

[0008] A method for cutting steel according to the present disclosure includes a preparation step of preparing steel, an adjustment step of forming a flame at the tip of a nozzle of a cutting device and adjusting the position of the nozzle relative to the steel based on the center of the flame, a preheating step of preheating the steel while maintaining the height of the nozzle adjusted in the adjustment step, and a cutting step of cutting the steel by moving the nozzle along the portion of the steel to be cut. In the adjustment step, a flammable mixed gas, which is a mixture of hydrogen gas and hydrocarbon gas, is supplied to the nozzle as a first combustion gas. In the preheating step and the cutting step, hydrogen gas is supplied to the nozzle as a second combustion gas. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a steel fusing device and a steel fusing method that are capable of performing gas fusing using 100% hydrogen gas and that allow the nozzle height to be easily adjusted to an appropriate position. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a flame formed at the tip of a nozzle. [Figure 2] FIG. 2 is a schematic diagram showing a steel material to be gas cut. [Figure 3] FIG. 3 is a system diagram showing a fusing device according to an embodiment. [Figure 4] FIG. 4 is a time chart illustrating the operation of the fusing device according to the embodiment. [Figure 5] FIG. 5 is an enlarged view showing the nozzle of the fusing device according to the embodiment. [Figure 6] FIG. 6 is a flowchart showing an outline of the blowout procedure. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Outline of the embodiment] First, an outline of the fusing device and fusing method according to the present disclosure will be listed and described. A steel fusing device according to the present disclosure includes an oxygen gas supply pipe connected to an oxygen gas supply source, a first pipe connected to a combustible mixed gas supply source, a second pipe connected to a hydrogen gas supply source, a combustion gas supply pipe to which the first pipe and the second pipe are connected via a switching mechanism, and a crater to which the oxygen gas supply pipe and the combustion gas supply pipe are respectively connected. The switching mechanism is capable of selectively switching between a first state in which the first pipe and the combustion gas supply pipe are connected to each other, and a second state in which the second pipe and the combustion gas supply pipe are connected to each other.

[0012] The inventors conducted extensive research into a method for using only hydrogen gas as the combustion gas during cutting and for easily adjusting the nozzle of the cutting device to an appropriate position. As a result, the inventors came up with the idea of ​​using a flammable mixed gas, separate from the hydrogen gas used during cutting, that would form a visible white core when adjusting the nozzle position. They then came up with the idea of ​​configuring a device equipped with a switching mechanism that can switchably connect a line for supplying hydrogen gas and a line for supplying a flammable mixed gas to a combustion gas supply pipe leading to the nozzle.

[0013] According to the above-described device, the position of the nozzle can be adjusted based on the visible white core, allowing cutting to be performed without significantly changing the method used in conventional gas cutting. According to the above-described device, the height of the nozzle can be easily adjusted to an appropriate position. Furthermore, according to the above-described device, a switching mechanism can selectively supply a flammable mixed gas or hydrogen gas to the combustion gas supply pipe. This configuration allows cutting using 100% hydrogen gas without changing the conventionally used nozzle. Furthermore, by supplying a flammable mixed gas and hydrogen gas to the same combustion gas supply pipe, there is little change in the flame state during the nozzle adjustment process and the flame state during the preheating process and cutting process, allowing cutting to be performed reliably.

[0014] The flammable mixed gas may contain 4.5% by volume or more and 12% by volume or less of ethylene, with the remainder being hydrogen gas and unavoidable impurities. When using a gas with this composition as the flammable mixed gas, the nozzle height can be adjusted in the same manner as in the past, and the cutting process can be performed using 100% hydrogen gas.

[0015] The flammable mixed gas supply source may be a container that contains the flammable mixed gas, and the hydrogen gas supply source may be a container that contains the hydrogen gas. By using a pre-mixed gas that is contained in a container as the flammable mixed gas, the fusing device can be configured simply. Furthermore, it is possible to supply a flammable mixed gas with a constant composition, making it easy to operate the device and enabling fusing to be performed stably.

[0016] A method for cutting steel according to the present disclosure includes a preparation step of preparing steel, an adjustment step of forming a flame at the tip of a nozzle of a cutting device and adjusting the position of the nozzle relative to the steel based on the center of the flame, a preheating step of preheating the steel while maintaining the height of the nozzle adjusted in the adjustment step, and a cutting step of cutting the steel by moving the nozzle along the portion of the steel to be cut. In the adjustment step, a flammable mixed gas, which is a mixture of hydrogen gas and hydrocarbon gas, is supplied to the nozzle as a first combustion gas. In the preheating step and the cutting step, hydrogen gas is supplied to the nozzle as a second combustion gas.

[0017] According to the above-described fusing method, 100% hydrogen gas can be used in the preheating and fusing processes. This reduces CO2 emissions and enables fusing of steel materials in a way that places less strain on the environment. Furthermore, the process of adjusting the nozzle position creates a flame containing a visible white core, eliminating the need for major modifications to the nozzle position adjustment method used in conventional gas fusing.

[0018] The above-described fusing method may further include, between the adjusting step and the preheating step, a switching step of operating a switching mechanism that supplies one of the first combustion gas and the second combustion gas to a combustion gas supply pipe connected to the nozzle, thereby switching the gas supplied to the combustion gas supply pipe from the first combustion gas to the second combustion gas. This configuration enables gas fusing using 100% hydrogen gas without changing a conventionally used nozzle. Furthermore, by using a switching mechanism to switch between the first combustion gas and the second combustion gas, the combustion gas can be changed quickly and reliably, and a versatile gas fusing method can be realized without requiring special adjustment methods or skilled techniques.

[0019] [Specific example of embodiment] Next, specific embodiments of the steel fusing device and steel welding method according to the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and their description will not be repeated. In this specification, hydrogen gas refers to a gas consisting of hydrogen and inevitable impurities. In this specification, hydrogen gas that is not a mixed gas is sometimes referred to as 100% hydrogen gas to distinguish it from mixed gas, but this does not refer only to a gas that is mathematically strictly composed of 100% hydrogen, but also includes gases that are generally commercially available as hydrogen gas.

[0020] FIG. 1 is a schematic diagram showing a tip used in gas cutting of steel and a flame formed at the tip of the tip. Referring to FIG. 1, a flame 100 is formed at the tip of tip 51. A white core 101 appears directly below (at the mouth of) tip 51. The white core 101, also called a white cone, is a bright white portion of the gas flame that forms at the base of the flame. A preheating flame 102 is formed around white core 101. The preheating flame 102 is formed by the combustion of a gas mixture formed by mixing combustion gas and oxygen gas at the tip. A cutting oxygen gas flow 103 is formed at the center of preheating flame 102. When cutting oxygen gas is not supplied, white core 101 appears as a cone-shaped portion. A white core can be seen in a flame using a combustion gas containing hydrogen gas and hydrocarbon gas as the combustion gas. A white core cannot be seen in a flame using only hydrogen gas as the combustion gas. In the fusing device and fusing method according to the present disclosure, the white core 101 forms a visible flame in the tip adjustment step, whereas the white core 101 forms an invisible flame in the preheating step and fusing step.

[0021] FIG. 2 is a schematic diagram showing a steel material to be gas cut. Referring to FIG. 2, a flame is applied to the steel material M to be cut. As is well known, a preheating flame 102 heats the surface of the steel material M, creating a portion m where the temperature reaches the combustion temperature of steel. A fusing oxygen gas flow 103 is blown onto the surface, causing the steel to combust and melt into slag, which is then blown away by the fusing oxygen gas flow 103 and cut. The distance between the nozzle 51 and the steel material M, i.e., the height of the nozzle 51 relative to the steel material M, is set based on the length of the white core 101. It has been discovered that, in the fusing device and fusing method according to the present disclosure, by using a visible white core 101 to set the height of the nozzle 51 and maintaining that height, fusing can be reliably performed during the preheating and fusing processes even if the white core 101 is not visible.

[0022] FIG. 3 is a system diagram showing a steel fusing apparatus according to an embodiment. Note that the system diagram shown in FIG. 3 omits some components other than those characteristic of the present disclosure, such as safety devices. Referring to FIG. 3 , the fusing apparatus 1 includes a combustible mixed gas cylinder 11 as a combustible mixed gas supply source, a hydrogen gas cylinder 12 as a hydrogen gas supply source, and an oxygen gas cylinder 13 as an oxygen gas supply source. In the fusing apparatus 1, three types of gas, namely, the combustible mixed gas, hydrogen gas, and oxygen gas, are switched as needed and supplied to the nozzle 51. In particular, the combustible mixed gas and hydrogen gas are selectively switched and supplied to the nozzle 51. The combustible mixed gas cylinder 11 is connected to a pipe 31 serving as a first pipe. The hydrogen gas cylinder 12 is connected to a pipe 32 serving as a second pipe. The pipes 31 and 32 are connected to a pipe 52 serving as a combustion gas supply pipe via a three-way valve 21 serving as a switching mechanism. The pipes 31 and 32 are each provided with a pressure gauge, a solenoid valve, and a safety device along the way. The pipes 31 and 32 are also provided with mass flow controllers 41 and 42, respectively.

[0023] The three-way valve 21 selectively switches between a state in which the pipe 31 and the pipe 52 are in communication with each other and a state in which the pipe 32 and the pipe 52 are in communication with each other. In other words, by switching the three-way valve 21, it is possible to selectively switch between a state in which the flammable mixed gas is supplied to the burner port 51 and a state in which hydrogen gas is supplied to the burner port 51.

[0024] The oxygen gas cylinder 13 is connected to a pipe 33 serving as an oxygen gas supply pipe. The pipe 33 branches into a pipe 53 for supplying preheating oxygen gas and a pipe 54 for supplying oxygen gas for fusing. The pipes 53 and 54 are each equipped with a pressure gauge, a solenoid valve, and a safety device. The pipe 53 is equipped with a mass flow controller 43. One end of the pipes 53 and 54 is connected to the nozzle 51.

[0025] The combustible mixed gas cylinder 11 contains a combustible mixed gas. The combustible mixed gas is a gas capable of forming a visible white core upon combustion. The combustible mixed gas is typically hydrogen gas containing a hydrocarbon gas such as ethylene or propylene. The combustible mixed gas preferably contains 4.5 to 12% by volume of ethylene, with the remainder consisting of 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. 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. Furthermore, a white core of an appropriate size can be formed with an oxygen flow rate equivalent to that used to form a preheating flame of 100% hydrogen gas. This facilitates the series of steps of forming a white core, adjusting the height of the nozzle, then switching the three-way valve to form a preheating flame using 100% hydrogen gas, and then performing the cutting process.

[0026] The hydrogen gas cylinder 12 contains hydrogen gas. The hydrogen gas cylinder may be a cylinder filled with commonly used hydrogen gas, or may be any other hydrogen gas container. The oxygen gas cylinder 13 contains oxygen gas. The oxygen gas cylinder may be a cylinder filled with commonly used oxygen gas, or may be any other oxygen gas container. Gas containers other than gas cylinders may be liquefied gas containers such as LGCs (Liquid Gas Containers) and CEs (Cold Evaporators), and can be selected depending on the size of the facility and the amount of gas used.

[0027] The fusing device according to the present disclosure can be implemented as part of an existing gas fusing machine or in combination with an existing gas fusing machine, which is not particularly limited, but may be, for example, a portal-type CNC cutting machine, a frame planer, a pattern-copy fusing machine, or the like.

[0028] 4 is a time chart illustrating the operation of the fusing device according to the embodiment. The fusing device 1 will be described with reference to FIGS.

[0029] [Adjusting the nozzle] When cutting steel, the position of the nozzle relative to the steel to be cut is adjusted before preheating and cutting begins. The nozzle position is determined by the horizontal position (also called the XY position) that matches the top surface of the steel and the cutting shape, and the height of the nozzle relative to the top surface of the steel (also called the Z position). The XY position can be set according to standard methods.

[0030] Referring to the time chart, the adjustment of the nozzle position includes times t1 to t2. When adjusting the Z-axis position, the three-way valve 21 is operated to connect the pipes 31 and 52. The three-way valve 21 may be automatically switched by a control program or manually operated by an operator. From times t1 to t2, the combustible mixed gas and preheating oxygen gas are supplied to the nozzle 51. The combustible mixed gas is supplied through pipes 31 and 52, and its flow rate is adjusted by the mass flow controller 41. The preheating oxygen gas is supplied through pipes 33 and 53, and its flow rate is adjusted by the mass flow controller 43. Ignition occurs in this state, and a flame is formed at the tip of the nozzle 51 by the combustion of the combustible mixed gas. A white core is formed in this flame, and the height of the nozzle relative to the steel (Z-axis position) is adjusted using the white core as a guide. The positional relationship between the white core and the steel is not particularly limited, and the nozzle position can be adjusted according to conventional knowledge.

[0031] [preheat] Between times t2 and t3, the three-way valve 21 is operated to switch to a state in which the pipes 32 and 52 are connected. By setting this state, hydrogen gas is supplied to the nozzle 51 through the pipe 52 from time t3 onwards. The period from time t3 to t4 (time T1) is a preheating period, during which hydrogen gas and preheating oxygen gas are supplied to the nozzle 51. The hydrogen gas is supplied through the pipes 32 and 52, and its flow rate is adjusted by the mass flow controller 42. The preheating oxygen gas is supplied through the pipes 33 and 53, and its flow rate is adjusted by the mass flow controller 43. The flow rate of the preheating oxygen gas circulating from time t3 to t4 may be the same as or different from the flow rate of the preheating oxygen gas circulating from time t1 to t2. It is preferable that they are the same. Ignition occurs in this state, and a flame is formed at the tip of the nozzle 51 by the combustion of the hydrogen gas. Although the white core of this flame cannot be seen, preheating can be carried out by maintaining the nozzle height adjusted in the previous process.

[0032] [Fusing] From time t4 to t5, oxygen gas for cutting is supplied to nozzle 51. The supply of oxygen gas for cutting is controlled by a solenoid valve attached to pipe 54. A flame is formed at the tip of nozzle 51 as hydrogen gas burns, and oxygen gas for cutting is sprayed from nozzle 51. Nozzle 51 moves in the X and Y directions along the predetermined cutting shape to perform cutting. When cutting is completed at time t5, the oxygen gas for cutting is turned off, and then the hydrogen gas and preheating oxygen gas are also turned off.

[0033] Fig. 5 is an enlarged view showing the tip of the fusing device according to the embodiment. The tip of the fusing device according to the present disclosure can be a known tip and is not particularly limited, but as an example, tip 51 shown in Fig. 5 can be preferably used.

[0034] Fig. 5(a) is a schematic cross-sectional view of the nozzle 51, and Fig. 5(b) is a view of the nozzle 51 as seen from the nozzle tip side. Referring to Fig. 5, the nozzle 51 is configured by combining a nozzle member 81, a cover member 82, and a core member 83. The cover member 82 is fitted onto the outside of the nozzle member 81. The lower end of the core member 83 is inserted and fixed between the nozzle member 81 and the cover member 82. A fusing oxygen gas passage 71 is provided inside the nozzle member 81 along the axial direction. A mixed gas passage 72 is formed between the outer peripheral surface of the nozzle member 81 and the inner peripheral surface of the cover member 82.

[0035] The core 83 is attached by inserting it into the socket portion connected to the ends of the pipes 52, 53, and 54. The socket portion is connected to the pipe 54, which is the passage for the fusing oxygen gas, the pipe 53, which is the passage for the preheating oxygen gas, and the pipe 52, which is the passage for the flammable mixed gas and hydrogen gas. When the core 83 is inserted into the socket portion and attached, the passage for the fusing oxygen gas in the socket portion is connected to the fusing oxygen gas passage 71 in the core 83. Furthermore, the passage for the preheating oxygen gas in the socket portion is connected to the groove 83a provided in the outer peripheral surface of the core 83. Furthermore, the combustion gas passage provided in the socket portion is connected to the groove 83b provided in the outer peripheral surface of the core 83.

[0036] Groove 83a and groove 83b are each connected to a mixing chamber 83e provided inside core 83. In mixing chamber 83e, preheating oxygen gas supplied through groove 83a is mixed with flammable mixed gas or hydrogen gas supplied through groove 83b. The mixed gas is discharged from the tip of nozzle 51 through mixed gas passage 72.

[0037] At the tip of the nozzle 51, the distance from the end face 81c of the tip of the nozzle member 81 to the end face 82c of the tip of the cover member 82 is 1 mm. According to this configuration, a pocket 88 having a depth of 1 mm is provided at the tip of the nozzle member 81 by the cover member 82.

[0038] The fusing device 1 according to the present disclosure can form a flame having a white core, for example, 6 to 8 mm in length, at the tip of the tip 51. Using this white core as a reference, the distance from the surface of the steel material to be cut to the tip 51 (the tip height) can be set to, for example, about 6 mm to 8 mm.

[0039] 6 is a flow chart showing an outline of the melt-cutting procedure. The melt-cutting method for steel material according to the present disclosure will be described with reference to FIG.

[0040] First, a steel material is prepared (S11) and the steel material is brought into a state where it can be fused.

[0041] Next, a combustible mixed gas (first combustion gas), which is a mixed gas of hydrogen gas and hydrocarbon gas, and preheating oxygen gas are supplied to the nozzle of the cutting device to form a flame. Specifically, as described above, a mixed gas of a combustible mixed gas supplied from a combustible mixed gas cylinder and oxygen gas supplied from an oxygen gas cylinder is supplied to the nozzle located at the tip of the torch. These gases are mixed inside the nozzle to form a mixed gas. A flame is formed by igniting this mixed gas. This flame has a visible white core. There are no particular restrictions on the length of the white core, but when attempting to cut a steel plate with a thickness of approximately 20 mm to 200 mm, for example, it is preferable to form a flame with a white core length of approximately 2 mm to 6 mm. The height of the nozzle is adjusted based on the white core (S12).

[0042] Next, the portion of the steel material to be cut is heated by the flame formed in step (S12) (S13). In step S13, hydrogen gas (second combustion gas) is supplied to the nozzle as combustion gas, and the steel material is heated by the preheating flame formed by combustion of the hydrogen gas. Step S13 is a preheating process.

[0043] Next, oxygen gas for cutting is ejected from the nozzle, and the oxygen gas is sprayed onto the portion of the steel material to be cut that has been heated by the flame. This burns and melts the steel material in that portion (S14). Furthermore, the molten steel material is removed by the spray of oxygen gas ejected from the nozzle. Cutting is performed in this manner. Furthermore, the nozzle is moved along the predetermined cutting shape to perform cutting (S15). Steps S14 and S15 constitute the cutting process. The steel material is cut by the above procedure. According to the steel cutting method of this embodiment, when adjusting the nozzle position, a combustible mixed gas is supplied to form a flame with a visible core, and when preheating and cutting, a flame is formed using only hydrogen gas as the combustion gas. In this way, gas cutting can be performed using 100% hydrogen gas, and the nozzle height can be easily adjusted to an appropriate position.

[0044] The conditions for the fusing process can be varied depending on various conditions and are not particularly limited. As an example, when fusing steel material with a thickness of approximately 15 mm to 50 mm, the flow rate of the preheating oxygen gas can be 6.4 L / min to 8.0 L / min, the flow rate of the hydrogen gas can be approximately 16.0 L / min, and the oxygen:hydrogen ratio can be approximately 0.4 to 0.5:1. The pressure of the preheating oxygen gas can be approximately 0.3 MPa, and the pressure of the hydrogen gas can be approximately 0.03 MPa. The pressure of the fusing oxygen can be approximately 0.5 MPa. The fusing speed can be approximately 300 mm / min to 450 mm / min. Furthermore, when fusing steel material with a thickness of approximately 50 mm to 150 mm, the flow rate of the preheating oxygen gas can be 7.0 L / min to 8.8 L / min, the flow rate of the hydrogen gas can be approximately 17.6 L / min, and the oxygen:hydrogen ratio can be approximately 0.4 to 0.5:1. The pressure of the preheating oxygen gas can be about 0.4 MPa, and the pressure of the hydrogen gas can be about 0.03 MPa. The pressure of the cutting oxygen can be about 0.5 MPa. The cutting speed can be about 200 mm / min to 250 mm / min.

[0045] The fusing device and fusing method according to the present disclosure were demonstrated. [Flame formation by ethylene-hydrogen mixed gas] Using hydrogen gas containing 5% by volume ethylene and hydrogen gas containing 10% by volume ethylene as the flammable mixed gas, a flame was generated under the flow rate conditions shown in Table 1, and the length of the white core formed was confirmed. A three-stage cutting tip (for hydrogen gas) was used as the tip. When hydrogen gas containing 5% by volume of ethylene was used as the combustible mixed gas, the oxygen flow rate in the nozzle adjustment process was the same as that used in the preheating and cutting processes.When hydrogen gas containing 10% by volume of ethylene was used as the combustible mixed gas, the oxygen flow rate in the nozzle adjustment process was assumed to be 40 to 50% of the oxygen flow rate used in the preheating and cutting processes.

[0046] [Table 1]

[0047] As shown in Table 1, when hydrogen gas containing 5% by volume of ethylene was used as the combustible mixed gas, a flame with a core length of 6 to 8 mm was formed at any oxygen / combustible mixed gas flow ratio between 0.4 and 0.57. Furthermore, when hydrogen gas containing 10% by volume of ethylene was used, a flame with a core length of 6 to 10 mm was formed at any oxygen / combustible mixed gas flow ratio between 0.4 and 0.75.

[0048] Furthermore, the flame core length was confirmed when different nozzles were used, using hydrogen gas containing 10% ethylene by volume. The nozzle numbers, gas flow rates, and flame core lengths used are shown in Table 2.

[0049] [Table 2]

[0050] As shown in Table 2, even when the tinder size was changed, a lower edge with a white core length of 6 to 8 mm could be obtained.

[0051] It has been confirmed that when cutting with 100% hydrogen gas, the optimum tip height is approximately 6 to 8 mm from the steel surface, and the above demonstration confirmed that a flame with a core length of approximately 6 to 10 mm can be formed using an ethylene-hydrogen mixed gas. It was thought that hydrogen gas containing 4.5 to 12 volume percent ethylene was appropriate as a flammable mixed gas.

[0052] [Cutting steel materials with hydrogen gas flames] Using the above method, the nozzle was adjusted and a demonstration experiment was conducted to cut steel using a hydrogen gas flame. The steel used was SS400 with thicknesses of 28mm, 45mm, and 100mm. A three-stage nozzle (for hydrogen gas) was used. The flow rates, flow rate ratios, and pressures of the preheating oxygen gas and hydrogen gas, as well as the pressure and cutting speed of the oxygen gas used for cutting, are summarized in Table 3.

[0053] [Table 3]

[0054] The steel material was fusion cut under the conditions shown in Table 3, and it was judged that fusion cutting was carried out well based on the state of the fusion cross section, fusion top surface and dross.

[0055] The embodiments disclosed herein are illustrative in all respects and should not be construed as limiting. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0056] 1 cutting device, 11 flammable mixed gas cylinder, 12 hydrogen gas cylinder, 13 oxygen gas cylinder, 21 three-way valve, 31, 32, 33, 52, 53, 54 piping, 41, 42, 43 mass flow controller, 71 oxygen gas passage for cutting, 72 mixed gas passage, 81 nozzle member, 82 cover member, 83 body, 88 pocket, 100 flame, 101 white core, 102 preheating flame, 103 oxygen gas flow for cutting.

Claims

1. an oxygen gas supply pipe connected to an oxygen gas supply source; a first pipe connected to a source of a combustible gas mixture; a second tube connected to a hydrogen gas source; a combustion gas supply pipe to which the first pipe and the second pipe are connected via a switching mechanism; a burner port to which the oxygen gas supply pipe and the combustion gas supply pipe are respectively connected; Equipped with the switching mechanism is capable of selectively switching between a first state in which the first pipe and the combustion gas supply pipe are in communication with each other and a second state in which the second pipe and the combustion gas supply pipe are in communication with each other; the flammable mixed gas contains 4.5% by volume or more and 12% by volume or less of ethylene, with the remainder being hydrogen gas and unavoidable impurities; Steel cutting equipment.

2. the flammable mixed gas supply source is a container that contains the flammable mixed gas, The hydrogen gas supply source is a container containing the hydrogen gas. The fusing device according to claim 1 .

3. a preparation step of preparing steel material; an adjusting step of forming a flame at a tip of a nozzle of a fusing device and adjusting the position of the nozzle relative to the steel material based on the core of the flame; a preheating step of preheating the steel material while maintaining the height of the nozzle adjusted in the adjusting step; a fusing step of fusing the steel material by moving the nozzle along a portion of the steel material to be fusing; Including, In the adjusting step, a flammable mixed gas, which is a mixed gas of hydrogen gas and hydrocarbon gas, is supplied to the nozzle as a first combustion gas, In the preheating step and the melt-cutting step, hydrogen gas is supplied to the nozzle as a second combustion gas. A method for cutting steel.

4. Furthermore, between the adjusting step and the preheating step, a switching step of operating a switching mechanism that supplies one of the first combustion gas and the second combustion gas to a combustion gas supply pipe connected to the burner port, thereby switching the gas supplied to the combustion gas supply pipe from the first combustion gas to the second combustion gas; The fusing method according to claim 3.

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