Cutting device, cutting method, and powder

Abstract

To provide a cutting device which can efficiently cut a cut object.SOLUTION: A nozzle part is connected to a body part of a cutting torch. The cutting device can blow out at least fuel gas and powder from the nozzle part. The powder contains silicon of 5-20% (wt%).SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to a cutting device, a cutting method, and a powder used for cutting, for example, reinforced concrete or other cutting objects. [Background technology]

[0002] In recent years, there has been an increase in cases where demolition work is required to remove existing structures before construction of new buildings can begin. Among existing structures, the most common method for demolishing sturdy frameworks, such as reinforced concrete structures, is to use large breakers. However, one of the issues is the vibrations that construction generates in the surrounding environment. Furthermore, in underground areas, despite the large cross-section of the foundation structure, work must be done in a confined space, limiting the use of large machinery. Therefore, there is a need to develop a construction method that can solve these issues.

[0003] Currently, cutting methods using wire sawing and core boring are used to suppress vibrations that occur when demolishing large cross-section concrete structures. However, the former has the problem that the wire saw must be installed around the periphery of the cutting area. The latter has the problem that steel materials such as rebars and steel frames that make up the structure can interfere with core boring. Therefore, the inventors have developed cutting equipment and methods that use hydrogen-based mixed gases to improve the efficiency of demolishing underground concrete structures and reduce the impact on the surrounding environment (Patent Documents 1-3).

[0004] The cutting devices and cutting methods disclosed in Patent Documents 1 to 3 use powder (which may also be called metal powder) to raise the temperature of the flame at the flame nozzle above the required temperature. This powder may be iron or aluminum only, or it may be mixed with other metals such as magnesium or used alone. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-138303 [Patent Document 2] Japanese Patent Publication No. 2023-014706 [Patent Document 3] Japanese Patent Application Publication No. 2023-114443 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, cutting devices and methods using mixed gases are effective in improving the efficiency of demolition and reducing the impact on the surrounding environment. Therefore, it is desirable to improve these cutting devices and methods to make them easier to use. Furthermore, as disclosed in Patent Documents 1-3, a mixed powder of iron and aluminum is added to the fuel gas, and a large amount of molten material (also called "molten slag," "slag," or "dross") is generated during cutting. The generated molten material cools and solidifies before flowing off, re-adhering, and adhering to the concrete makes it difficult to remove. Therefore, the molten material needs to be re-melted and removed, but removing the molten material requires a lot of time and high temperatures, which can be a burden on the cutting worker.

[0007] An object of the present invention is to provide a cutting device that can efficiently cut an object to be cut. [Means for solving the problem]

[0008] (1) In order to solve the above problems, the cutting device of the present invention comprises: A cutting device having a nozzle connected to a main body of a cutting torch and capable of ejecting at least fuel gas and powder from the nozzle, The powder contains silicon at a ratio of 5 to 20% (by weight). (2) The cutting efficiency when the silicon content of the powder is in the range of 5 to 15% is at least four times higher than the cutting efficiency when the silicon content of the powder is 20%. [Effects of the Invention]

[0009] According to the present invention, a cutting device capable of efficiently cutting an object to be cut can be provided. [Brief explanation of the drawings]

[0010] [Figure 1A] 1 is a diagram showing a schematic diagram of a cutting device 10. FIG. [Figure 1B] FIG. 2 is a diagram for explaining a cutting device according to an embodiment of the present invention. [Figure 2] 1A is a front view illustrating the cutting torch with the middle part thereof omitted, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A. [Figure 3] 2(c) is a front view of the cutting torch of FIG. 2(a) rotated 90 degrees around the longitudinal axis, and FIG. 2(d) is a cross-sectional view taken along line BB in FIG. 2(c). [Figure 4] (a) is a diagram showing the tip surface of the crater, and (b) is a diagram showing the side surface of the crater. [Figure 5] (a) to (d) are figures for explaining the nozzle holder according to the embodiment, (a) is a diagram showing the side, (b) is a diagram showing the rear end face, (c) is a cross-sectional view along line AA in (b), and (d) is a cross-sectional view along line BB in (b). [Figure 6] FIG. 10 is a partial cross-sectional view showing the state in which the burner is attached to the burner holder. [Figure 7] 1A and 1B are diagrams for explaining cutting of an object to be cut by a cutting torch. [Figure 8] FIG. 10 is a diagram illustrating the state in which the cutting torch has entered the cleavage portion. [Figure 9] 10 is an explanatory diagram showing the function of a powder introduction passage. FIG. [Figure 10] (a) to (e) are diagrams for explaining other types of tip holders, where (a) is a diagram showing the side, (b) is a cross-sectional view along the AOC line of (c), (c) is a diagram showing the rear end face, (d) is a cross-sectional view along the BOD line of (c), and (e) is a cross-sectional view along the EE line of (d). [Figure 11]10 is used, and (b) is an explanatory diagram showing the path of powder when the type of tip holder shown in FIG. 5 according to the embodiment is used. [Figure 12] 10 is a table showing comparative examples in which the composition of the powder is changed. [Figure 13] FIG. 1A is an explanatory diagram showing a photographic image of cutting work when the powder according to the embodiment is used, and FIG. 1B is an explanatory diagram showing a photographic image of cutting work when a conventional powder is used. [Figure 14] 10 is a graph showing experimental results of the relationship between the mixing ratio of silicon contained in the powder and cutting efficiency. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Outline of the description of the embodiment> Below, a cutting device, a cutting method, and powders (including silicon) used therein according to an embodiment of the present invention will be described. Note that as the cutting device according to this embodiment, a cutting device similar to that disclosed in Patent Document 3 (JP 2023-114443 A) can be used. Therefore, in the description of the cutting device, many parts are similar to those of the cutting device disclosed in Patent Document 3.

[0012] <Cutting device and cutting method> 1 is a schematic diagram of a cutting device 10 according to an embodiment of the present invention. This cutting device 10 includes a cutting torch 11 and a supply hose 18. Of these, the cutting torch 11 has a cylindrical main body 14, the axial length of which is long enough to be held by a cutting operator with one or both hands. The overall length, external dimensions, and weight of the cutting torch 11 are such that an operator can hold it in their hand (with gloved hands for safety) and perform work agilely; for example, the diameter is 25 to 40 mm, the overall length is about 500 to 2000 mm, and the weight is about 10 kg or less.

[0013] Specifically, the axial length of the main body 14 may be set to a length of approximately 1 m to 2 m. The main body 14 is not limited to a straight tube, and may be tapered or arc-shaped, for example. Furthermore, the main body 14 may be bent at some intermediate position to form a dogleg or L-shape. The cross-sectional shape of the main body 14 may also be polygonal, such as triangular or rectangular.

[0014] A plurality of supply hoses 18 are connected to the base end side (right side in FIG. 1) of the cutting torch 11. Each supply hose 18 is made of a material such as rubber or resin. As shown in FIGS. 2 and 3, the supply hoses 18 are connected to various pipes provided in the main body 14 of the cutting torch 11, including a fuel gas supply pipe 20, a cutting oxygen supply pipe 21a, a preheating oxygen supply pipe 21b, a powder supply pipe 22, and a cooling water supply pipe 23.

[0015] Fuel gas, cutting oxygen, preheating oxygen, and powder are supplied from an adjustment supply unit (not shown) to the fuel gas supply pipe 20, cutting oxygen supply pipe 21a, preheating oxygen supply pipe 21b, and powder supply pipe 22 via supply hoses 18 connected to each pipe. Details of the gases and powder will be described later. Note that Figure 3(c) shows the cutting torch of Figure 2(a) rotated 90 degrees around the longitudinal axis, with a portion cut away.

[0016] The cooling water supply pipe 23 described above circulates cooling water (not shown) inside the main body 14. The cooling water supply pipe 23 has a forward (outgoing (IN)) and a return (returning (OUT)) pipe. The cooling water supply pipe 23 has a portion (hereinafter referred to as "cooling water IN") 23a that guides the cooling water from the base end side of the cutting torch 11 toward the tip end side (from the top to the bottom in FIG. 1), and a portion (hereinafter referred to as "cooling water OUT") 23b that guides the cooling water from the tip end side of the cutting torch 11 toward the base end side (from the left to the right in FIG. 1). Here, hatching or shading indicating a cross section is omitted in FIGS. 2 and 3.

[0017] As shown in Fig. 1, the flame nozzle 15 located at the tip end of the cutting torch 11 is composed of a nozzle 16 as a nozzle portion. As will be described later, the nozzle 16 is connected to a nozzle receiver 51 as a nozzle receiver, and is attached to the main body 14 via the nozzle receiver 51. Of these, the nozzle 16 is formed in a cylindrical shape, as shown in Figs. 4(a) and (b). Here, the nozzle 16 is shown only in Figs. 1 and 4(a) and (b), and Figs. 2 and 3 show the nozzle 16 removed.

[0018] As shown in Figure 4(a), multiple types of holes are opened on the tip surface 35 of the nozzle 16 (the surface where the flame nozzle 15 is located). These holes are a cutting oxygen nozzle 31, a fuel gas nozzle 32, a preheating oxygen nozzle 33, and a powder nozzle 34. The cutting oxygen nozzle 31 is located in the center of the nozzle 16, and the fuel gas nozzles 32 are located on the outside of it on a concentric circle centered on the cutting oxygen nozzle 31. In the example of Figure 4, there are four fuel gas nozzles 32.

[0019] The preheating oxygen nozzles 33 are arranged outside the fuel gas nozzles 32 on a concentric circle centered on the cutting oxygen nozzle 31. In the example of FIG. 4, there are eight preheating oxygen nozzles 33. The powder nozzles 34 are arranged outside the preheating oxygen nozzles 33 on a concentric circle centered on the cutting oxygen nozzle 31. In the example of FIG. 4, there are also eight powder nozzles 34.

[0020] The opening of each of the injection ports 31-34 is circular, and all of the openings have the same diameter. Each of the injection ports 31-34 has the same opening dimensions and opening area on the tip surface 35 of the nozzle 16. The total opening area of ​​each type of injection port 31-34 is determined by the number of openings. The tip surface 35 is formed as a flat surface (a flush surface) that includes each of the injection ports 31-34.

[0021] The number and arrangement of the injection ports 31-34 are not limited to the example shown in Fig. 4(a) and can be modified in various ways. For example, the opening shape of some or all of the injection ports can be rectangular (square). Furthermore, the opening dimensions and opening area of ​​the injection ports 31-34 can be the same for each type, and the opening dimensions and opening area of ​​at least some types can be different from those of the other types.

[0022] Although detailed illustrations are omitted, the cutting oxygen nozzle 31, the fuel gas nozzle 32, the preheating oxygen nozzle 33, and the powder nozzle 34 are spatially connected to the cutting oxygen nozzle passage, the fuel gas nozzle passage, the preheating oxygen nozzle passage, and the powder nozzle passage, respectively, inside the nozzle 16.

[0023] The injection passage for cutting oxygen (not shown) extends along the axis inside the nozzle 16 and opens to the rear end face 36 (FIG. 4(b)) of the nozzle 16. In contrast, the injection passages for fuel gas, preheating oxygen, and powder (all not shown) are formed in an L-shape so as to extend in the axial and radial directions of the nozzle 16.

[0024] The numbers of injection passages for fuel gas, preheated oxygen, and powder correspond to the numbers of fuel gas injection nozzles 32, preheated oxygen injection nozzles 33, and powder injection nozzles 34 described above, and are 4, 8, and 8, respectively. The injection passages for fuel gas, preheated oxygen, and powder open to the bottoms of annular grooves 42-44 (FIG. 4(b)) formed in the outer peripheral surface of the nozzle 16.

[0025] In the example of FIG. 4(b), annular groove 42 is a fuel gas annular groove assigned to a fuel gas injection passage (not shown). Annular groove 43 is a preheated oxygen annular groove 43 assigned to a preheated oxygen injection passage (not shown), and annular groove 44 is a powder annular groove 44 assigned to a powder injection passage (not shown). A plurality of injection passages (not shown) for fuel gas, preheated oxygen, and powder are formed at the bottom of the corresponding annular grooves 42 to 44. Each injection passage (not shown) opens at approximately equal intervals at the bottom of the corresponding annular groove 42 to 44 and is spatially connected to the corresponding annular groove 42 to 44.

[0026] Here, the annular grooves 42 to 44 may be formed in a continuous O-shape around the entire circumference of the outer periphery of the nozzle 16. Alternatively, the annular grooves 42 to 44 may be of an intermittent type in which a plurality of arc-shaped (also called C-shaped) grooves are arranged intermittently in the circumferential direction.

[0027] The annular grooves 42-44 open in an O-shape (or discontinuous shape) into a tapered section 46 formed on the rear end side of the nozzle 16 (the right end side in the drawing of FIG. 4(b)). The tapered section 46 is formed on the rear end side of the male thread section 47 located midway in the axial direction of the nozzle 16. The tapered section 46 is formed in the region between the male thread section 47 and the rear end face 36, and has a shape that becomes thinner as it approaches the rear end side of the nozzle 16 (towards the rear end face 36). The nozzle 16 is then removably fixed to the nozzle receiver 51 (FIG. 1) by inserting the tapered section 46 into the nozzle receiver 51 (described later).

[0028] Next, the tip receiver 51 will be described with reference to Figure 1 and Figures 5(a) to (d). The tip receiver 51 is formed in a cylindrical shape overall, and as shown in Figure 1, is detachably attached to the main body 14 of the cutting torch 11. As shown in Figures 5(c) and (d), the tip receiver 51 has a tip insertion hole 52 into which the tip 16 is inserted, and the tip insertion hole 52 opens in a perfect circle at the tip end surface 53. A thread groove (symbol omitted, female thread groove) 56 is formed on the inner circumferential surface of the tip insertion hole 52 on the tip side (tip end surface 53 side) of the tip receiver 51.

[0029] A tapered section 54 is formed at the rear end (towards the rear end face 57) of the tip nozzle insertion hole 52, and the tapered section 54 tapers toward the rear. An inner peripheral surface 55 of the tapered section 54 is a tapered surface that is continuous in the circumferential and axial directions. One end of a cutting oxygen introduction passage 61 opens at the rear end (rear end) of the tip nozzle insertion hole 52, and the other end of the cutting oxygen introduction passage 61 opens at the center of the rear end face 57 of the tip nozzle receiver 51, as shown in Figure 5(b).

[0030] Four passages are formed around the tapered portion 54. These passages are a fuel gas introduction passage 62, a preheating oxygen introduction passage 63, and two powder introduction passages 64. As shown in FIG. 5(b), the introduction passages 62 to 64 open on concentric circles centered on the cutting oxygen introduction passage 61 at the rear end surface 57. Of these, the two powder introduction passages 64 are formed symmetrically (line symmetrically and point symmetrically) with respect to the tip receiver 51.

[0031] As shown in Figures 5(c) and (d), connection holes 67 to 69 are formed at the end of one end (the side of the tip surface 53) of the fuel gas introduction passage 62, the preheated oxygen introduction passage 63, and the powder introduction passage 64.

[0032] These connection holes 67-69 are a fuel gas connection hole 67, a preheating oxygen connection hole 68, and a powder connection hole 69. Each of the connection holes 67-69 extends in the radial direction of the burner tip receiver 51 and is spatially connected to the burner tip insertion hole 52. Each of the connection holes 67-69 constitutes a part of the fuel gas introduction passage 62, the preheating oxygen introduction passage 63, and the powder introduction passage 64, respectively.

[0033] Furthermore, each of the connection holes 67-69 opens to the outer peripheral surface 58 of the burner holder 51. By opening each of the connection holes 67-69 to the outer peripheral surface 58 of the burner holder 51, it becomes easier to process each of the introduction passages 62-64. However, the openings of each of the connection holes 67-69 in the outer peripheral surface 58 are closed while each of the introduction passages 62-64 is secured.

[0034] In other words, only the open ends of each of the connection holes 67-69 on the outer circumferential surface 58 are blocked, and each of the introduction passages 62-64 is formed so as not to impede the flow of fuel gas, spare oxygen, and powder. In order to block the openings of each of the connection holes 67-69, for example, it is possible to press-fit a columnar body 100 made of the same material as the tip receiver 51 into the opening so that no gaps are formed, and then polish the protruding portion to integrate it with the tip receiver 51 so that it is not noticeable.

[0035] Of the connection holes 67-69, the fuel gas connection hole 67 (Fig. 5(d)) is formed at a position closest to the rear end face 57 compared to the other connection holes 68, 69 (Figs. 5(a) and 5(b)). The two powder connection holes 69 (Fig. 5(b)) are formed at a position closest to the front end face 53 compared to the other connection holes 67, 68 (Fig. 5(d)). The two powder connection holes 69 (Fig. 5(b)) are arranged on the same line at 180-degree intervals. The preheating oxygen connection hole 68 (Fig. 5(d)) is formed at a position between the fuel gas connection hole 67 (Fig. 5(d)) and the powder connection hole 69 (Fig. 5(b)).

[0036] As shown in Figure 5(d), the fuel gas introduction passage 62 is formed parallel to the cutting oxygen introduction passage 61. As shown in Figures 5(c) and 5(d), the preheating oxygen introduction passage 63 and the powder introduction passage 64 are inclined so as to move away from the axis of the tip receiver 51 from the rear end face 57 toward the front end face 53.

[0037] The cutting oxygen introduction passage 61, the fuel gas introduction passage 62, the preheating oxygen introduction passage 63, and the powder introduction passage 64 are connected to the cutting oxygen supply pipe 21a, the fuel gas supply pipe 20, the preheating oxygen supply pipe 21b, and the powder supply pipe 22 shown in Figures 2 and 3. Here, the bundle of the cutting oxygen supply pipe 21a, the fuel gas supply pipe 20, the preheating oxygen supply pipe 21b, and the powder supply pipe 22 is twisted in the main body 14 so as to align with the positions of the cutting oxygen introduction passage 61, the fuel gas introduction passage 62, the preheating oxygen introduction passage 63, and the powder introduction passage 64.

[0038] Next, as shown in FIG. 6 , the burner tip 16 is removably screwed into the burner tip insertion hole 52 of the burner tip receiver 51. When the burner tip 16 is screwed all the way into the burner tip receiver 51, the tapered portion 46 of the burner tip 16 is inserted into the tapered portion 54 of the burner tip receiver 51 and comes into contact (surface contact) with the inner circumferential surface 55 of the tapered portion 54 of the burner tip receiver 51. In this manner, the burner tip 16 and the burner tip receiver 51 are connected with their tapered portions 46, 54 in contact with each other. Here, the tapered portions 46, 54 are not limited to being in direct contact with each other without an intervening object. For example, an intervening object such as a tapered tubular object or a curved sheet-like object may be provided between the tapered portions 46, 54. This intervening object may be rigid or flexible. Furthermore, the intervening object may exhibit sealing properties (e.g., airtight sealing properties). Furthermore, instead of being limited to the case in this embodiment where the nozzle 16 is the male side and the nozzle receiver 51 is the female side, for example, the nozzle 16 may be the female side and the nozzle receiver 51 may be the male side, and the nozzle 16 and the nozzle receiver 51 may be connected.

[0039] The tapered portion 46 of the nozzle 16 is tapered and does not have any outwardly protruding portions. The inner peripheral surface 55 of the tapered portion 54 is also tapered and does not have any inwardly protruding portions. Therefore, the tapered portion 46 of the nozzle 16, except for the openings of the fuel gas annular groove 42, the preheating oxygen annular groove 43, and the powder annular groove 44 (tapered surfaces), comes into surface contact with the inner peripheral surface 55 of the tapered portion 54.

[0040] When the tip 16 is attached to the tip receiver 51 in this manner, the cutting oxygen nozzle 31 (Fig. 4(a)) of the tip 16 is spatially connected to the cutting oxygen introduction passage 61 of the tip receiver 51. In addition, the fuel gas annular groove 42, preheating oxygen annular groove 43, and powder annular groove 44 of the tip 16 are also spatially connected to the fuel gas introduction passage 62 (Fig. 5(d)), preheating oxygen introduction passage 63 (Fig. 5(d)), and powder introduction passage 64 of the tip receiver 51.

[0041] Cutting oxygen is introduced into the tip 16 through the cutting oxygen introduction passage of the tip receiver 51 and is sprayed from the cutting oxygen nozzle 31 (Fig. 4(a)) of the tip 16. Fuel gas, preheated oxygen, and powder are introduced into the tip 16 through the fuel gas introduction passage 62 (Fig. 5(d)), preheated oxygen introduction passage 63 (Fig. 5(d)), and powder introduction passage 64 of the tip receiver 51 and are sprayed from the fuel gas nozzle 32, preheated oxygen nozzle 33, and powder nozzle 34 (all Fig. 4(a)) of the tip 16. The cutting oxygen, fuel gas, preheated oxygen, and powder are sprayed from the tip 16 to form a mixed gas.

[0042] The fuel gas can be hydrogen gas or various other gases, but hydrogen-rich gas is particularly preferable. Examples of hydrogen-rich gas include hydrogen gas (100%) and a mixture of hydrogen gas and a hydrocarbon gas (with a hydrogen mixing ratio of 50% or more).

[0043] When hydrogen-rich gas is used, radiant heat from the workpiece can be suppressed during cutting. Hydrogen-rich gas also excels in directivity when sprayed. This suppresses the temperature felt by the worker and overheating of the cutting torch 11. Furthermore, the flame can be sprayed precisely at the desired location.

[0044] The cutting oxygen has the functions of burning the powder and discharging the molten material from the cutting target (e.g., reinforced concrete). The powder has the function of raising the flame temperature. For example, instead of the iron and aluminum powder used in the invention of Patent Document 3, a mixed powder of iron and silicon (Si) (or a mixed powder of iron, aluminum, and silicon) is used as the powder. Details of the silicon-mixed powder will be described later. When silicon is mixed, the target material is melted using the heat generated by oxidation of silicon, as in the case of aluminum. In this case, iron oxide is used as the base to enhance fluidity, and a powder with a high heat of oxidation reaction (here, silicon) is mixed to improve cutting ability. However, this is not limited to this, and powders of various compositions can be used as long as they can raise the flame temperature above the required temperature and facilitate the handling of the resulting molten material (hereinafter referred to as "dross"). The composition of the silicon-containing powder may, for example, contain multiple types of metal components and silicon, or it may contain silicon as well as other non-metallic components. By changing the mixing ratio of the composition in the powder depending on the configuration (characteristics such as structure and composition) of the workpiece (here, workpiece 72 to be cut, which will be described later in FIG. 6, etc.), the fluidity of the workpiece (molten material) that has been heated and melted can be improved, and the dischargeability can be improved. Powders containing silicon will be described later.

[0045] The type of metal contained in the powder may be iron only or aluminum only. Magnesium or the like can be mixed with other metal powders or used alone in the powder. Furthermore, the metal component in the powder can be a mixture of iron and other metal powders, and the iron content (also referred to as the "mixing ratio" or "mixing proportion") in the powder can be relatively high (greater than 50%). Preferably, the iron content can be set to, for example, 65 to 90% (by weight). Furthermore, the iron content can be changed (determined) taking into account the worker's condition (working posture, work content, etc.).

[0046] At least some of the powder components constituting the powder have a size that is visible (also referred to as "particle size" or "grain size"). This makes it possible to make the mixed gas visible even if the other components of the mixed gas (fuel gas such as hydrogen gas and various oxygen species) are not visible. Then, the mixed gas can be ignited after visually checking the injection state (speed, flow rate, directness, etc.) of the mixed gas.

[0047] 7 illustrates an example of an operator 70 holding and operating a cutting torch 11 to cut an object 72 made of reinforced concrete or the like. To cut the object 72, fuel gas and preheated oxygen supplied to the cutting torch 11 are sprayed from the cutting torch 11 at high pressure. Powder sprayed from the cutting torch 11 is mixed with the mixed gas of fuel gas and preheated oxygen, and the mixed gas (mixture) is ignited. More specifically, it is believed that the powder is heated by the mixed gas, and then ignited by the cutting oxygen.

[0048] A flame 74 is ejected from the cutting torch 11 so as to travel in a straight line. FIG. 7 shows a schematic diagram of the flame 74 hitting and reflecting off the workpiece 72. An operator 70 faces the tip of the cutting torch 11 toward the workpiece 72 and heats the surface of the workpiece 72. After the preheating stage is completed, cutting oxygen is added to the preheating oxygen to maintain (or intensify) the flame 74. Then, as cutting oxygen and powder are supplied, the high-temperature flame 74 is ejected and heats the workpiece 72.

[0049] After the cutting oxygen has been supplied, the cutting temperature of the flame 74 reaches 1500 to 2000°C or higher due to the action of the powder containing silicon, exceeding the melting point of the workpiece 72. The high-temperature flame 74 is then blown onto the workpiece 72, melting the part of the workpiece 72 that the flame 74 hits.

[0050] In the object 72 to be cut, a cracking section 76 (FIG. 8) is formed by the flame 74, where the concrete and rebar are partially removed. As the cracking section 76 is formed, the molten object to be cut (molten material) flows out. For example, the operator 70 gradually advances the tip side of the cutting torch 11 into the cracking section 76, deepening the cracking section 76. FIG. 8 schematically shows the state in which the tip side of the cutting torch 11 has advanced into the cracking section 76.

[0051] The worker 70 moves the cutting torch 11 forward and in a suitable combination of horizontal and vertical movements. The worker 70 then sequentially cuts out the object 72 to be cut into, for example, plate-like or rectangular parallelepiped shapes, and proceeds with the demolition of a building or the like made of reinforced concrete. Cooling water flows through the cutting torch 11 via a cooling water supply pipe 23, and this cooling water circulates between the inside and outside of the cutting torch 11. This prevents the cutting torch 11 from excessively increasing in temperature during cutting work.

[0052] 7 and 8 also show a shielding metal plate 78. This shielding metal plate 78 is formed into a plate shape using a fire-resistant metal material. The shielding metal plate 78 can be used by the operator 70 alone or in combination with a chamber section (not shown) as needed to prevent radiant heat and sparks. A rectangular opening 79 is provided in the shielding metal plate 78.

[0053] Although not shown, the shielding metal plate 78 can be used by, for example, having another worker hold it, placing it on a stand, supporting it with a lifting mechanism (such as a crane or winch), or leaning it against the object to be cut 72. The worker 70 can insert the tip end of the cutting torch 11 into the opening 79 and perform the cutting work described above while being protected from radiant heat and sparks.

[0054] If the opening 79 is rectangular, for example, the cutting torch 11 can be moved linearly in the horizontal or vertical direction using the edge of the opening 79 as a guide. That is, for example, a portion of the cutting torch 11 between the tip end and the operator 70 is placed on the lower edge of the opening 79, and the operator 70 moves the cutting torch 11 while keeping it in contact with the lower edge of the opening 79. Then, the cutting torch 11 moves along the shape of the lower edge of the opening 79, and the workpiece 72 is cut linearly.

[0055] In the cutting torch 11 used as shown in Figures 7 and 8, powder introduced into the tip receiver 51 (Figures 5(a) to (d)) passes through powder introduction passages 64, as shown schematically in Figure 9. Figure 9 shows an enlarged cross section of one of the powder introduction passages 64. The powder that enters the powder introduction passage 64 passes through the powder introduction passage 64 and heads toward the tip 16. In Figure 9, the flow of powder is indicated by arrow P.

[0056] As described above, the powder introduction passage 64 is inclined away from the axis of the tip receiver 51. Therefore, the powder (arrow P) advances toward the columnar body 100 that closes the powder connection hole 69. Furthermore, the powder flows into the powder connection hole 69 after approaching the columnar body 100 that closes the end of the powder connection hole 69. In other words, the powder is ejected from the powder introduction passage 64 toward the inner end surface 102 of the columnar body 100 at the boundary between the powder introduction passage 64 and the powder connection hole 69.

[0057] In the powder connection hole 69, a bag-shaped bent portion 104 is formed around the inner end surface 102 of the columnar body 100. For this reason, powder may accumulate around the inner end surface 102 of the columnar body 100. However, because the powder is ejected from the powder introduction passage 64 toward the inner end surface 102 of the columnar body 100, the powder that reaches the columnar body 100 or the bent portion 104 is blown away by the following powder.

[0058] The powder connection hole 69 opens facing the powder annular groove 44 of the nozzle 16, and the blown-off powder is introduced directly from the powder connection hole 69 into the powder annular groove 44 of the nozzle 16. Here, the inner end surface 102 of the columnar body 100 forms the innermost part of the powder connection hole 69 (the innermost part on the radially outer side of the nozzle receiver 51).

[0059] According to the cutting device 10 of this embodiment as described above, the tip 16 and tip receiver 51 are connected with their tapered portions 46, 54 in contact (surface contact). This allows the tip 16 and tip receiver 51 to be in close contact with each other on a linear surface (conical surface) with few steps. Furthermore, no space can be created between the tip 16 and tip receiver 51 except for the passage of fuel gas, reserve oxygen, and powder. This minimizes the occurrence of unevenness or steps between the tip 16 and tip receiver 51. This also prevents powder from accumulating on the unevenness or steps. This also applies when using powder containing silicon, as described below. According to the inventors' findings, replacing conventional aluminum with silicon further reduces powder accumulation.

[0060] Furthermore, according to the cutting device 10, the tip receiver 51 is formed with a powder introduction passage 64, and a part of the powder introduction passage 64 serves as a powder connection hole 69 that opens into the tapered surface of the tapered portion 54. Therefore, the powder introduction passage 64 can be directly spatially connected to the tip 16. Compared to tip receivers 81 of the type shown in Figures 10(a) to 10(e), this cutting device 10 can reduce the space where powder can accumulate as much as possible, and is therefore easier to maintain.

[0061] 10(a) to (e) is a different type of tip receiver from tip receiver 51 of the present embodiment shown in Figures 5(a) to (d). In tip receiver 81 of the type shown in Figures 10(a) to (e), an annular powder groove 86 is formed around tip insertion hole 82. The presence of annular powder groove 86 increases the area where powder can accumulate, making tip receiver 81 and tip 16 more likely to stick together.

[0062] Explaining in more detail, the type of fire nozzle holder 81 shown in Figure 10 is similar to the type of fire nozzle holder 51 shown in Figure 5 in that the tapered portion 88 is in surface contact with the tapered portion 46 of the fire nozzle 16. However, a plurality of annular grooves 84-86 are formed around the fire nozzle insertion hole 82, and each of the annular grooves 84-86 is a recessed portion that protrudes (is recessed) outside the fire nozzle insertion hole 82 (outside in the radial direction).

[0063] Each of the annular grooves 84 to 86 is spatially connected to a fuel gas introduction passage 92, a preheated oxygen introduction passage 93, and one powder introduction passage 94. Fuel gas, preheated oxygen, and powder are supplied to each of the introduction passages 92 to 94. Here, reference numeral 91 in Figures 10(b) to 10(d) denotes a cutting oxygen introduction passage used to supply cutting oxygen.

[0064] Although not shown, a tip 16 as shown in Figures 4(a) and (b) is screwed all the way into tip receiver 81 shown in Figure 10. Tapered portion 46 of tip 16 enters tapered portion 88 of tip receiver 81 and comes into contact with an inner peripheral surface 89 of tapered portion 88 of tip receiver 81. The annular grooves of the tip 16 for cutting oxygen, the annular groove 42 for fuel gas, the annular groove 43 for preheating oxygen, and the annular groove 44 for powder are then spatially connected to the annular grooves of the tip receiver 81 for fuel gas, the annular groove 85 for preheating oxygen, and the annular groove 86 for powder.

[0065] The cutting oxygen, fuel gas, preheating oxygen, and powder are introduced into the nozzle 16 through the respective introduction passages 91 to 94 of the nozzle receiver 81. Then, the cutting oxygen, fuel gas, preheating oxygen, and powder are sprayed as a mixed gas from the cutting oxygen nozzle 31, fuel gas nozzle 32, preheating oxygen nozzle 33, and powder nozzle 34 of the nozzle 16, in the same manner as when the nozzle receiver 51 shown in Figures 5(a) to (d) is used.

[0066] However, as mentioned above, the tip holder 81 is provided with an annular powder groove 86 that protrudes outward (is recessed). Figure 11(a) shows a schematic cross section of the tip holder 81 of the type shown in Figure 10 with the tip 16 connected. Figure 11(a) shows a simplified vertical cross section of the tip holder 81 and tip 16 when viewed from the tip side (left side in Figure 1).

[0067] 11(a), the annular powder groove 86 is spatially connected to the annular powder groove 44 of the burner nozzle 16, and together with the annular powder groove 44 of the burner nozzle 16, they form a large-capacity (large-volume) and large-area space. This increases the volume and area of ​​the portion with which the powder can come into contact. As a result, powder can accumulate inside the annular powder groove 86 in the burner nozzle receiver 81, increasing the space where the powder can accumulate.

[0068] Therefore, powder easily accumulates in the space between the tip receptacle 81 and the tip 16. If the accumulated powder melts and solidifies, the tip receptacle 81 and the tip 16 stick together, making it difficult to remove the tip 16. If the powder is made of a low-melting-point component, such as aluminum, or if it contains a low-melting-point component, the powder is likely to stick together. To prevent this sticking between the tip receptacle 81 and the tip 16, it is necessary to interrupt the cutting operation immediately and perform maintenance work. In maintenance work, the tip 16 is removed from the tip receptacle 81, and the tip receptacle 81 and the tip 16 are cleaned. Frequent maintenance work increases the work time and labor required, making it difficult to shorten the construction period and reduce the labor required.

[0069] In contrast, Figure 11(b) shows a schematic cross section of the burner tip holder 51 of the type shown in Figures 5(a) to (d) in a state where the burner tip 16 is connected. Figure 11(b) shows a simplified vertical cross section of the burner tip holder 51 and the burner tip 16 when viewed from the tip side (the left side in Figure 1).

[0070] As shown in Figure 11 (b), no annular powder groove is provided in tip holder 51. Tip 16 has an annular powder groove 44 for receiving powder, and powder connection hole 69 in tip holder 51 opens toward annular powder groove 44. Powder that passes through powder connection hole 69 in powder introduction passage 64 is introduced directly from powder connection hole 69 in tip holder 51 into annular powder groove 44 in tip 16.

[0071] For this reason, the volume and area of ​​the portion of tip receiver 51 that can come into contact with powder are small, leaving less room for powder to accumulate. Furthermore, compared to tip receiver 81 shown in Figure 10, powder is less likely to accumulate on the inner periphery of tip receiver 51. As a result, powder is also less likely to accumulate in powder connection hole 69, and powder connection hole 69 and the boundary between tip receiver 51 and tip 16 are kept clean for a long period of time. Furthermore, adhesion between tip receiver 51 and tip 16 can be prevented, which makes it easier to remove tip 16 and eliminates the need for frequent maintenance work.

[0072] In the case of the fire tray 81 shown in Figures 10 and 11(a), maintenance work was required, for example, about once every 30 minutes. However, in the case of the fire tray 51 shown in Figures 5 and 11(b), work could be continued for a day without maintenance. Reducing the frequency of maintenance work is important for shortening construction time and reducing labor hours.

[0073] Furthermore, according to the cutting device 10 of this embodiment, the tip receiver 51 is provided with a plurality of (here, two) powder introduction passages 64, and the powder is introduced into the tip 16 through the plurality of powder introduction passages 64. This allows the supply of powder to the tip 16 to be well balanced. Also, the powder can be sprayed from the tip 16 with good linearity.

[0074] To explain in more detail, for example, if there is one powder introduction passage 94 (one passage, one system) as in the case of the tipper receiver 81 shown in Figure 10, the amount of powder passing through the powder introduction passage 94 (amount of powder per unit time) to supply the same amount of powder to the tipper 16 will be greater than if there are multiple powder introduction passages 64 as in the example of Figure 5. Furthermore, gravity acts on the powder, and a small amount of powder may fall and remain inside the powder introduction passage 94. Furthermore, when there is one powder introduction passage 94, the amount of powder remaining in the powder introduction passage 94 will also be greater than when there are multiple powder introduction passages.

[0075] However, by providing multiple powder introduction passages 64 as in the example of Figure 5, the amount of powder flowing through each powder introduction passage 64 can be reduced. This allows the powder to be supplied to the nozzle 16 in a balanced and efficient manner. This also makes it possible to spray the powder from the nozzle 16 in a straight line.

[0076] Furthermore, in the nozzle 16, the powder is simultaneously sprayed from a plurality of (eight in this example) powder spray nozzles 34 arranged concentrically. Therefore, the powder can be guided to the nozzle 16 via a plurality of paths and sprayed from the nozzle 16. This also enables the nozzle 16 to spray powder in a straight line. The number of powder introduction passages 64 is not limited to a plurality, and may be, for example, a single passage.

[0077] 9, the powder introduction passage 64 is inclined away from the axis of the tip receiver 51, and the powder is injected toward the inner part of the powder connection hole 69 (defined by the inner end surface 102 of the columnar body 100). This prevents the powder from accumulating in the inner part of the powder connection hole 69. Even if the powder does accumulate, the accumulated powder can be blown away by the subsequent powder. This also prevents the powder from accumulating in the tip receiver 51.

[0078] <Recycling Dross> As explained above, when cutting a structure (the object 72), the object 72 melts due to heating (heat melting), generating molten material (dross). Gas cutting with the cutting torch 11 uses a mixed gas containing iron powder and aluminum powder to simultaneously cut reinforcing steel and concrete, so the generated molten material (dross) is a mixture of molten iron, aluminum, their metal oxides, and concrete, and is molten concrete (concrete dross) containing metal elements. This molten concrete flows down from the cracked portion 76 toward the ground or splashes toward the worker 70. Furthermore, the molten concrete cools when exposed to air while flowing down from the cracked portion 76 (or sometimes drooping) or while adhering to the cut surface (such as the cracked portion 76).

[0079] When the molten concrete cools to a certain temperature, it solidifies and becomes a solid. The solidified molten concrete is separated from the cutting target 72 and can be called a "separated solid." Because the separated solid contains metal elements, it has a higher specific gravity than concrete alone. This separated solid can be reused as fire-resistant aggregate, etc. Possible uses for the separated solid include cutting it into rectangular parallelepiped shapes to use like bricks, or creating ornamental pieces that take advantage of the amorphous shape it has when solidified.

[0080] <About powders containing silicon> The improvement in the handling of the powder in the above-mentioned tip 16 and tip receiver 51 is even more remarkable when silicon is used instead of aluminum, or when aluminum and silicon are mixed together. The advantages of including silicon in the powder are explained below.

[0081] The reason why the inventors originally included aluminum in the powder when cutting structures such as reinforced concrete was to make it easier to melt the concrete surface. The reason why adding aluminum to the powder makes it easier to melt the concrete surface is thought to be because aluminum has the material properties of a low melting point and a high calorific value.

[0082] However, the melting point of aluminum oxide is very high at 2072°C, as shown in the cell at the intersection of "Aluminum" and "Oxide Melting Point [°C]" in the comparison table in Figure 12. For this reason, when melting powder (aluminum oxide dross) that has been generated, solidified, and re-fused, the temperature of the dross must be raised again to its melting point. This means that re-melting the dross requires a lot of time and effort.

[0083] The inventors considered changing the composition of the powder to facilitate the handling of such dross (as well as the handling of the cutting device 10, the cutting method, the powder, etc.). They selected silicon as a new component to be included in the powder. When silicon is included in the powder, the main component of the resulting dross is silicon oxide. As shown in the cell at the intersection of "silicon" and "oxide melting point [°C]" in the diagram of FIG. 12, the melting point of silicon oxide is 1610°C, which is significantly lower than the melting point of aluminum oxide (2072°C). Therefore, remelting dross that has solidified after generation does not require as much time or effort as aluminum oxide.

[0084] Furthermore, as shown in the "Heat generation amount [kJ / g]" column in the chart in Figure 12, the heat generation amount for the iron and aluminum mixed powder is 31.1 [kJ / g], while that for the iron and silicon mixed powder is 30.6 [kJ / g]. In other words, the amount of heat generated when silicon is included in the powder is almost the same as the amount of heat generated in the conventional example where aluminum is included in the powder, so the efficiency of cutting the object is almost the same when silicon is included in the powder and when aluminum is included in the powder.However, the temperature required to re-melt the dross generated by cutting is significantly lower when silicon is included in the powder than when aluminum is included in the powder.Therefore, when silicon is included in the powder, it is possible to reduce the impact of radiant heat on the person cutting (worker) compared to the conventional example where aluminum is included in the powder.

[0085] Furthermore, by including silicon in the powder as in this embodiment, the amount of dross generated during cutting can be reduced compared to the conventional example in which silicon is not included. FIG. 13(a) shows the state during cutting when the powder includes silicon, and FIG. 13(b) shows the state during cutting when the powder does not include silicon (when aluminum is used). The photographic image in FIG. 13(b) shows the generated dross 110 flowing and hanging down. In contrast, the photograph in FIG. 13(a) does not show any dross. In this way, by including silicon in the powder, the generation of dross can be suppressed. Furthermore, the dross becomes easier to handle, which results in easier cutting.

[0086] Furthermore, by including silicon in the powder as in this embodiment, the re-welded dross can be easily peeled off from the cutting object and crushed, making the dross removal easier than when using the conventional example in which aluminum is included in the powder. Although analysis of these points has not yet been sufficient, it is thought that the use of silicon can weaken the dross, making it easier to crush and peel off.

[0087] The advantages (benefits, effects) described here are obtained whether the aluminum in conventional powders is replaced with silicon or when aluminum and silicon are mixed. Increasing the silicon content has significant advantages in terms of dross suppression, remelting, and removal work.

[0088] Furthermore, experiments conducted in accordance with the present invention have shown that increasing the amount of silicon makes it easier for the powder to clog the tip receiver 51 and tip 16 before being sprayed. Therefore, simply using silicon or increasing the silicon ratio makes the powder more likely to clog, and it cannot be said that the cutting device 10, cutting method, and powder handling are easier. Therefore, a future challenge is to find the optimal silicon ratio that makes it difficult for the powder to clog and provides advantages such as dross suppression, remelting, and removal work.

[0089] In this situation, the cutting device 10, cutting method, and powder according to this embodiment intentionally use an element (silicon) that makes the powder more likely to clog, but prioritize suppressing the amount of dross generated, remelting the dross that has solidified after generation, and removing the dross that has solidified. In addition, in order to use silicon that is more likely to clog, it is effective to combine it with the tip receiver 51 and tip 16, which do not easily accumulate powder, as in this embodiment.

[0090] Conventionally, various elements have been used as mixed elements in liquid fluxes or vaporized fluxes to suppress burrs during cutting. However, such conventional techniques do not facilitate powder handling, suppress the amount of dross generated, facilitate remelting of solidified dross, or facilitate the removal of solidified dross, as in the present embodiment. Therefore, the cutting device 10, cutting method, and powder of the present embodiment differ from the conventional techniques in terms of fundamental technical concepts, technical configurations, etc.

[0091] Furthermore, since the dross can be easily handled, as described above, when the dross is reused, the work of separating and collecting the dross is easy.

[0092] Furthermore, if we focus only on the oxide melting point of the oxide melting points and calorific values ​​shown in Figure 12, the oxide melting point of manganese is 1785°C (for MnO) or 1564°C (for Mn3O4), which is lower than that of aluminum and closer to that of silicon (1610°C). Therefore, it may be possible to use manganese instead of silicon.

[0093] <<Silicon mixing ratio contained in powder>> As mentioned above, adding silicon to the powder lowers the temperature required to remelt the dross, thereby reducing the impact of radiant heat on workers. It also reduces the amount of dross generated when cutting the workpiece. Furthermore, the dross that has re-melted to the workpiece can be easily peeled off or crushed.

[0094] However, if the amount of silicon is increased, a phenomenon occurs in which the powder tends to clog the nozzle holder 51 and the nozzle 16 before being sprayed.

[0095] For this reason, a suitable silicon mixing ratio is required from the viewpoints of preventing clogging of the powder, suppressing the generation of dross, and simplifying remelting and removal operations.

[0096] <Silicon mixing ratio> Fig. 14 is a graph showing the experimental results of the relationship between the mixing ratio of silicon contained in the powder and cutting efficiency. The horizontal axis of the graph shown in Fig. 14 is the mixing ratio (wt%) of silicon contained in the powder, and the vertical axis is cutting efficiency.

[0097] As shown in Figure 14, the cutting efficiency is approximately 3 when the silicon mixing ratio is 2.5%, approximately 5.3 to 5.7% when the silicon mixing ratio is 5%, approximately 5.1 when the silicon mixing ratio is 10%, approximately 5 when the silicon mixing ratio is 15%, and approximately 1.1 when the silicon mixing ratio is 20%.

[0098] From these results, it is found that a silicon mixing ratio in the range of 5 to 15% is preferable, and next, if the silicon mixing ratio is 2.5 to 20%, cutting can be performed with a certain degree of cutting efficiency.

[0099] <Experimental Method> The experimental method used to obtain the results shown in FIG. 14 will be described below.

[0100] <Preparation> Five types of powder were prepared, with silicon content adjusted to 2.5%, 5%, 10%, 15%, 20%, etc. The powders could contain iron, aluminum, etc. in addition to silicon. The weight of the powder was measured to achieve the desired content ratio.

[0101] <Cutting the object to be cut> One of the five types of powder described above was stored in a tank, and the tank was connected to the cutting torch 11 via a supply hose 18. The flow rates of the fuel gas, oxygen, and powder were adjusted and ejected as a flame 74 from the nozzle 16 of the cutting torch 11. The flame 74 was directed toward the object to be cut (such as reinforced concrete).

[0102] <Cutting efficiency> Our The time was measured based on when the flame 74 reached the object to be cut. The time until the object to be cut and the cut distance of the object to be cut were measured, and the cutting efficiency was calculated.

[0103] For each of the five types of powder, the cutting time and cutting distance were measured and the cutting efficiency was calculated.

[0104] The cutting efficiency may be calculated by measuring the consumption of fuel gas, oxygen, and powder instead of measuring the cutting time and cutting distance.

[0105] <Examples of inventions that can be extracted from the embodiments> For example, the following inventions can be extracted from this embodiment. (1) A cutting device in which a nozzle part (such as nozzle 16) is connected to a main body part (such as main body part 14) of a cutting torch (such as cutting torch 11) and capable of ejecting at least fuel gas and powder from the nozzle part, The powder contains silicon mixed at a ratio of 5 to 20% (by weight). (2) The cutting efficiency when the silicon content of the powder is in the range of 5 to 15% is at least four times higher than the cutting efficiency when the silicon content of the powder is 20%.

[0106] <Other> Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and many modifications are possible within the scope of the technical concept of the present invention. The described embodiment is merely an example of a specific embodiment for carrying out the present invention, and the technical scope of the present invention should not be interpreted as being limited thereby.

[0107] The cutting torch 11 can be held by the hand of the worker 70, but the way in which the cutting torch 11 is supported does not necessarily have to be by the worker 70 directly holding it in his hand. For example, it is also possible to provide a holding device (not shown) for the cutting torch 11 and support the cutting torch 11 using this holding device. Examples of holding devices include relatively lightweight, simple types (such as holder types, stand types, and handle types) and heavy machinery attachments that can be attached to heavy machinery.

[0108] Furthermore, various objects other than reinforced concrete can be used as the cutting object 72. For example, the cutting object 72 can be an object made of acrylic resin glass, a gas tank, or a soil column wall (an H-shaped steel beam embedded in cement-mixed soil as a core material). Further, the cutting object 72 can be an object at a construction site, an object at a demolition site, or a structure other than a structure containing iron. [Explanation of symbols]

[0109] 10 Cutting device 11 Cutting torch 14 Main body 16 Crater 18 Supply Hose 20 Fuel gas supply pipe 21a Cutting oxygen supply pipe 21b Preheated oxygen supply pipe 22 Powder supply pipe 23 Cooling water supply pipe 31 Cutting oxygen nozzle 32 Fuel gas nozzle 33 Preheating oxygen nozzle 34 Powder nozzle 42 Annular groove for fuel gas 43 Annular groove for preheating oxygen 44 Powder annular groove 46 Tapered section 51 Fire Nozzle 53 Tip surface 54 Tapered section 61 Cutting oxygen inlet passage 62 Fuel gas inlet passage 63 Preheated oxygen introduction passage 64 Powder introduction passage 67 Fuel gas connection hole 68 Preheated oxygen connection hole 69 Powder connection hole 72 Cutting object

Claims

1. A cutting device having a nozzle connected to a main body of a cutting torch and capable of ejecting at least fuel gas and powder from the nozzle, The powder contains silicon mixed at a ratio of 5 to 20% (by weight).

2. The cutting device according to claim 1, wherein the cutting efficiency when the silicon content of the powder is in the range of 5 to 15% is at least four times higher than the cutting efficiency when the silicon content of the powder is 20%.

Images