Powder cutting method

Abstract

To make it possible to improve work efficiency and can achieve improvement of safety by significantly reducing a preheating time when piercing a general soft steel.SOLUTION: A piercing method for piercing a material W to be cut comprising a general soft steel by use of a gas cutting nozzle 2 has: a process in which cut oxygen and a preheating gas are ejected from the gas cutting nozzle 2; and a process in which powders T are supplied toward a preheating flame air stream R comprising the cut oxygen and the preheating gas ejected from the gas cutting nozzle 2. According to the method, the powders T are supplied in a direction along the preheating flame air stream R.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention is a powder cutting method By law Regarding. [Background technology]

[0002] Conventionally, when cutting a workpiece made of ordinary mild steel using a gas cutting tip, as shown in Patent Document 1, it is common to preheat the workpiece for a long period of time, for example, 1 to 5 minutes, before piercing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 48-41957 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional methods for cutting materials made of ordinary mild steel require a considerable amount of preheating time during the piercing process, which increases the total time required for cutting, leaving room for improvement in this regard.

[0005] In cutting non-ferrous metals, a known method involves feeding a ferrous material into a preheated flame emitted from a gas cutting tip, burning iron powder to enhance the oxidation reaction and raise the temperature, which then melts the base material and cuts it. However, if this method of feeding a ferrous material into a preheated flame is used to cut ordinary mild steel, it generates fumes and increases cutting costs, making it difficult to apply to this type of cutting. In addition, in the past, there were cases where iron wire such as copper wire was used as the iron material to be supplied to the preheating flame, but this required the skilled technique of the worker to properly time the supply, and the quality was not stable. Moreover, when the worker supplied the copper wire to the cutting oxygen stream being sprayed into the preheating flame above the material to be cut, high-temperature slag exceeding 1500°C was scattered in the vicinity of the worker, so there was a need for further improvements in safety from the viewpoint of workability.

[0006] The present invention has been made in consideration of these circumstances, and aims to provide a powder cutting method, a powder supply nozzle, and a powder cutting nozzle that can increase work efficiency by significantly shortening the cutting time of ordinary mild steel, and also improve safety. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following means. The powder cutting method of the present invention is a powder cutting method in which a gas cutting tip is used to supply powder made of iron powder to a workpiece made of general mild steel to cut it, and the gas cutting tip is arranged so that it can spray cutting oxygen and preheating gas, which is a mixture of preheating oxygen and a flammable gas, toward the workpiece, and the powder is supplied toward a preheating flame airflow made of the preheating gas sprayed from the gas cutting tip.

[0008] In addition, in the powder cutting method of the present invention, the powder is supplied from the outer periphery of the nozzle of the gas cutting tip toward the preheating flame airflow, forming a powder flow surrounding the preheating flame airflow, and the powder flow caused by the powder extends in a slit shape in the direction of the powder ejection, forming a non-supply area where the powder is not supplied.

[0009] In addition, the powder cutting method of the present invention involves ejecting the preheating gas from the gas cutting tip and supplying powder toward the preheating flame stream consisting of the preheating gas ejected from the gas cutting tip, thereby generating red-hot powder in the preheating flame stream, and the red-hot powder is placed around a fixed ejection point of the cutting oxygen stream, and the cutting oxygen is supplied to the red-hot powder around the fixed ejection point to pierce the material to be cut.

[0010] In addition, the powder cutting method of the present invention includes a gas cutting process that continues from the piercing process and cuts the workpiece by moving the gas cutting tip, using the through hole created by the piercing as the cutting starting point, and before the gas cutting process, the powder continues to be supplied until it passes through the slag that has adhered to the upper surface of the workpiece by the piercing, and after the passage, the supply of the powder is stopped and then the gas cutting process is started.

[0011] In addition, the powder supply nozzle of the present invention is a powder supply nozzle for performing powder cutting on a workpiece made of ordinary mild steel by attaching it to a gas cutting tip that is capable of spraying cutting oxygen and preheating gas, which is a mixture of preheating oxygen and flammable gas, toward the workpiece, which is made of ordinary mild steel, and is equipped with a powder supply path that extends circumferentially along the outer periphery of the gas cutting tip and supplies powder made of iron powder, and a powder outlet that sprays the powder toward the preheating flame airflow made of the preheating gas sprayed from the gas cutting tip.

[0012] In addition, the powder supply nozzle of the present invention has an inner tube that fits around the gas cutting tip and an outer tube that is arranged on the outer periphery of the inner tube, and the powder outlet is arranged between the inner tube and the outer tube and is formed in a ring shape when viewed from the nozzle axial direction.

[0013] In addition, in the powder supply nozzle of the present invention, the powder outlet is provided with a partition portion that divides the outlet in a circumferential direction around the nozzle axis, and the partition portion connects the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube.

[0014] In the powder supply nozzle according to the present invention, the width dimension in the circumferential direction of the partition section is smaller than the distance between the partition sections adjacent to each other in the circumferential direction.

[0015] In the powder supply nozzle according to the present invention, the partition portions are provided at four locations spaced at intervals of 90 degrees in the circumferential direction.

[0016] In addition, the powder supply nozzle of the present invention is controlled separately as a first control that controls the start and stop of the supply of the cutting oxygen and the preheating gas ejected from the gas cutting tip, and a second control that controls the start and stop of the supply of the powder ejected from the powder ejection port.

[0017] A powder cutting nozzle according to the present invention includes the above-described powder supply nozzle and the gas cutting tip that is provided so that the powder supply nozzle can be attached. [Effects of the Invention]

[0018] The powder cutting method, powder supply nozzle, and powder cutting nozzle according to the present invention can significantly reduce the time required to cut ordinary mild steel, thereby increasing work efficiency and improving safety. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a half-longitudinal cross-sectional view showing the overall configuration of a cutting nozzle according to an embodiment of the present invention. [Figure 2] 1, and is a front view of the cutting nozzle as seen from the tip end side. [Figure 3] 2 is a view taken along the line X2-X2 in FIG. 1, and is a rear view of the cutting nozzle as seen from behind. [Figure 4] FIG. 10 is a diagram showing a state of piercing using a cutting nozzle. [Figure 5] FIG. 5 is a cross-sectional view taken along line X3-X3 in FIG. 4, showing the powder flow region. [Figure 6] 10(a) to 10(d) are explanatory views of the powder piercing operation. [Figure 7] 1A and 1B are schematic diagrams showing test methods according to examples, in which (a) is a comparative example in which no powder is supplied, and (b) is an example in which powder is supplied. [Figure 8] FIG. 10 is a front view of a cutting nozzle according to a modified example, as viewed from the tip side. DETAILED DESCRIPTION OF THE INVENTION

[0020] An embodiment of the present invention will be described with reference to Figures 1 to 6. Note that the dimensions of each component have been adjusted appropriately to make the drawings easier to see.

[0021] FIG. 1 is a semi-longitudinal cross-sectional view showing the overall configuration of a cutting nozzle 1 of this embodiment. FIG. 2 is a view taken along line X1-X1 in FIG. 1, and is a front view of the cutting nozzle 1 as seen from the tip side. FIG. 3 is a view taken along line X2-X2 in FIG. 1, and is a rear view of the cutting nozzle 1 as seen from the rear. FIG. 4 is a diagram showing a state of piercing using the cutting nozzle 1. FIG. 5 is a cross-sectional view taken along line X3-X3 in FIG. 4, and is a diagram showing the region of the powder flow Ta. FIG. 6 is an explanatory diagram of the powder piercing operation. In FIGS. 1 and 3, the gas cutting tip 2 has been omitted for clarity.

[0022] The gas cutting method according to this embodiment is a method for cutting a workpiece W (see FIGS. 4 and 7) made of general mild steel using a powder cutting method performed using a cutting nozzle 1 (powder cutting nozzle) shown in Fig. 1. That is, the cutting nozzle 1 can be used to pierce the workpiece W or to make a cut from an end of the workpiece W. With the cutting nozzle 1 of this embodiment, for example, the workpiece W placed on a substantially horizontal surface on a mounting table (not shown) is pierced, and then cutting is performed using the piercing as a cutting starting point.

[0023] 1 to 3, cutting nozzle 1 includes gas cutting tip 2 and powder supply nozzle 3. Cutting nozzle 1 has powder supply nozzle 3 detachably attached to the outer periphery of gas cutting tip 2. Here, in the cutting nozzle 1, the downstream side of the nozzle axis O where the cutting oxygen and preheating gas are ejected is called the tip side, and the side opposite to the tip side is called the base side.

[0024] The gas cutting tip 2 is a tip that is provided so as to be able to spray cutting oxygen and preheating gas, which is a mixture of preheating oxygen and flammable gas, toward the workpiece W, and is used when cutting the workpiece W. Here, the combustible gas may be LPG, acetylene, propylene, LNG, hydrogen, etc., and one of these may be used, or a preheating gas made by mixing these with preheating oxygen may also be used.

[0025] The gas cutting tip 2 includes an inner mandrel 2A having a cutting oxygen supply passage 21, an outer tip 2B through which the inner mandrel 2A is inserted, and a nozzle (not shown). The inner core rod 2A has a long cylindrical shape that tapers toward the tip. The inner core rod 2A is screwed into the nozzle head at the base end in the direction of the nozzle axis O. This allows the inner core rod 2A to be fitted into the nozzle head and integrated with the other parts. The inner core rod 2A is made of brass, for example, which has high thermal conductivity and heat resistance and is also economical in terms of manufacturing costs.

[0026] The inner core rod 2A has a cutting oxygen supply passage 21 extending along the nozzle axis O in the longitudinal direction. The cutting oxygen supply passage 21 communicates with the external space at its tip. A cutting oxygen nozzle 22 for spraying cutting oxygen is formed at the tip of the cutting oxygen supply passage 21 on the tip surface 2a of the inner core rod 2A. The cutting oxygen that has passed through the cutting oxygen supply passage 21 is sprayed forward from the cutting oxygen nozzle 22.

[0027] The inner core rod 2A also has a preheating gas supply passage 23 extending along the nozzle axis O outside the cutting oxygen supply passage 21. The preheating gas supply passage 23 is connected to the outside space at its tip. At the tip of the preheating gas supply passage 23, a plurality of slit-shaped preheating gas outlets 24 are formed on the tip surface 2a of the inner core rod 2A, extending radially from the cutting oxygen outlet 22 when viewed from the direction of the nozzle axis O. The preheating gas that has passed through the preheating gas supply passage 23 is ejected forward from the preheating gas outlets 24.

[0028] The outer nozzle 2B has a long cylindrical shape and is concentrically fitted to the inner mandrel 2A when viewed in the nozzle axial direction. The outer nozzle 2B forms a preheat gas supply path 23 between the inner surface 2c of the outer nozzle 2B and the outer surface 2b of the inner mandrel 2A, through which preheat gas, a mixture of preheated oxygen and combustion gas, passes. A powder supply nozzle 3 is attached to the outer surface of the outer nozzle 2B.

[0029] Next, a detailed description will be given of the configuration of powder feed nozzle 3. As shown in Figures 1 to 3, powder feed nozzle 3 is provided separately from gas cutting tip 2. Powder feed nozzle 3 forms powder feed path 31 for supplying powder T to the outer periphery of gas cutting tip 2, and has powder outlet 32 ​​for spraying powder T.

[0030] The powder supply nozzle 3 includes an inner cylinder 35 that fits around the gas cutting tip 2, an outer cylinder 36 (outer peripheral wall) that is positioned on the outer periphery of the inner cylinder 35, and a tip stop nut 34 for locking the gas cutting tip 2 inserted inside the inner cylinder 35. The tip stop nut 34, inner cylinder 35, and outer cylinder 36 each have a circular cross-sectional shape. The inner surfaces 34a, 35b of the connecting portion that connects the tip stop nut 34 and inner cylinder 35 in the nozzle axial direction are formed to be approximately flush with each other. The gas cutting tip 2 is inserted and fitted into the tip stop nut 34 and inner cylinder 35 from the base end. The tip end of the tip stop nut 34 and the base ends of the inner cylinder 35 and outer cylinder 36 are formed with female threads 3a that coaxially connect them. The nozzle retaining nut 34, the inner cylinder 35 and the outer cylinder 36 are integrally assembled by fastening the screw 3b shown in FIG. 3 to the female threaded portion 3a.

[0031] 1, the shape of the inner surface 35b of the inner cylinder 35 matches the outer peripheral surface 2d of the gas cutting tip 2, and the diameter decreases toward the tip. A tip tapered portion 351 is formed on the tip side of the outer peripheral surface 35a of the inner cylinder 35, and the outer diameter decreases toward the tip.

[0032] The outer cylinder 36 has the same length in the nozzle axial direction as the inner cylinder 35. The outer cylinder 36 has a cylindrical base end portion 361 that is disposed on the base end side and extends concentrically in the nozzle axial direction, and a conical tapered portion 362 that is connected to the tip side of the base end portion 361. The tapered portion 362 has a shape that becomes thinner as it approaches the tip side.

[0033] The powder supply path 31, through which the powder T is supplied, is formed between the inner cylinder 35 and the outer cylinder 36. A closing flange 35c that protrudes radially outward is provided around the entire circumference on the base end side of the inner cylinder 35. The closing flange 35c is in liquid-tight contact with the inner circumferential surface 36a on the base end side of the outer cylinder 36. As a result, the powder T supplied into the powder supply path 31 is ejected from the powder ejection port 32 on the tip side.

[0034] A plurality of (here, two) powder introduction joints 37 communicating with the powder supply passage 31 are attached to the base end portion 361 by screw fastening. The powder introduction joints 37 are connected to a powder supply device (not shown), and powder is supplied from this powder supply device into the powder supply passage 31. As shown in Fig. 3, the attachment angle θ between the two powder introduction joints 37 as viewed from the nozzle axial direction is set to 60°. The attachment angle θ of powder introduction joint 37 is preferably set so that the powder is supplied uniformly to powder supply path 31. Therefore, the best attachment angle θ is, for example, two attachment points at 180° intervals or three attachment points at 120° intervals. However, in consideration of the connection between the piping (not shown) connecting powder introduction joint 37 and the powder supply device, the two attachment points may be arranged close to one side, as in this embodiment.

[0035] 2, powder outlet 32 ​​is disposed between outer peripheral surface 35a of inner cylinder 35 and inner peripheral surface 36a of outer cylinder 36, and is formed in a ring shape when viewed in the direction of the nozzle axis. Powder outlet 32 ​​further includes a plurality of (four in this embodiment) partition ribs 33 (partition portions) that divide it in the circumferential direction around the nozzle axis. That is, partition ribs 33 are spaced apart at 90° intervals in the circumferential direction.

[0036] A plurality of partition ribs 33 are arranged at regular intervals around the circumferential direction of the powder outlet 32, and connect the outer peripheral surface 35a of the inner tube 35 and the inner peripheral surface 36a of the outer tube 36. The partition ribs 33 are provided at four locations at 90° intervals around the circumferential direction. As shown in FIG. 1, the partition ribs 33 extend from the tips of the inner tube 35 and the outer tube 36 toward the base ends. The area in which the partition ribs 33 are arranged is a range that radially faces the tip tapered portion 351 of the inner tube 35. Here, the circumferential width of the partition ribs 33 is smaller than the distance between adjacent partition ribs 33 in the circumferential direction.

[0037] Powder T ejected from powder outlet 32 ​​of powder supply nozzle 3 is supplied from the outer periphery of the outlet of gas cutting tip 2 toward preheating flame current R, forming powder flow Ta that surrounds preheating flame current R. By providing powder outlet 32 ​​with partition rib 33, as shown in Figure 5, powder flow Ta from this powder T extends in a slit shape in the ejection direction of powder T, forming a non-supply region Tb where powder T is not supplied.

[0038] Next, we will explain the operations involved in carrying out a piercing method for piercing a workpiece W made of general mild steel using the cutting nozzle 1, and a gas cutting method for cutting the workpiece W using this piercing method, as well as the functions of the powder cutting method, powder supply nozzle, and powder cutting nozzle of the present embodiment described above.

[0039] First, as shown in FIG. 2, the cutting nozzle 1 to be used is an integrated gas cutting tip 2 to which a powder supply nozzle 3 is attached. 2 and 4, preheating gas, which is a mixture of preheating oxygen and a combustible gas, is supplied to preheating gas supply passage 23 of gas cutting tip 2 of cutting nozzle 1, and this preheating gas is ejected to the outside from preheating gas outlet 24 to generate a preheating flame. At the same time, cutting oxygen is supplied to cutting oxygen supply passage 21 and ejected from cutting oxygen outlet 22. Furthermore, in powder supply nozzle 3, powder T is supplied to powder supply passage 31 and ejected from powder outlet 32. At this time, powder T ejected from powder outlet 32 ​​is supplied toward preheating flame airflow R made of preheating gas. In Figure 4, for ease of viewing, the powder T (powder flow Ta) is shown ejected along the outer periphery of the preheating flame airflow R, but the powder T is actually supplied in a direction that intersects with the flow direction of the preheating flame airflow R.

[0040] In this embodiment, the powder nozzle 32 is disposed on the outer periphery of the cutting oxygen nozzle 22 and the preheating gas nozzle 24 of the gas cutting tip 2, so that the powder T ejected from the powder nozzle 32 is supplied along the outer periphery of the preheating flame current R. In other words, the preheating flame current R is covered with the powder current Ta of the powder T. As described above, a non-supply region Tb is formed in the powder flow Ta, so the preheating flame airflow R is not entirely covered by the powder flow Ta, but rather a portion of the powder flow Ta is open in the shape of a slit.

[0041] The ejected powder T is supplied to the preheating flame airflow R inside the powder flow Ta, where it is sufficiently heated and melted before being ejected toward the workpiece W made of ordinary mild steel. Moreover, the powder T is not scattered outward and lost, and most of the powder T can be burned efficiently.

[0042] More specifically, as shown in Figures 6(a) to 6(d), preheating gas is ejected from the gas cutting tip 2, and powder T is supplied toward the preheating flame R formed by the preheating gas ejected from the gas cutting tip 2, thereby generating red-hot powder T3 in the preheating flame R. In Figures 6(a) to 6(d), reference symbol T1 indicates the powder immediately after ejection, reference symbol T2 indicates the powder in the process of becoming red-hot, and reference symbol T3 indicates the red-hot powder. The red-hot powder T3 is then positioned around a fixed ejection point Va of the cutting oxygen stream V. By supplying cutting oxygen to the red-hot powder T3 around the fixed ejection point Va, an oxidation reaction occurs all at once, allowing piercing or cutting of the workpiece W in an extremely short preheating time.

[0043] In this way, in this embodiment, the powder cutting method can be applied to the workpiece W made of general mild steel, and the cutting time can be significantly reduced, thereby improving work efficiency and improving safety. Therefore, the combustion ratio of the powder T increases, the exothermic reaction becomes stronger, and the combustion efficiency increases, melting the base material of the workpiece W. At the same time, the combustion products are blown away by the mechanical energy of the preheated flame airflow R, making it easy to pierce or cut into the workpiece W.

[0044] In this way, by supplying powder T to a preheating flame current R consisting of a preheating gas obtained by mixing preheating oxygen and a combustible gas, the workpiece W is pierced to form a through hole P. Furthermore, in this embodiment, piercing can be started immediately without the need for a long preheating period of, for example, 1 to 5 minutes as in the past. Moreover, as described above, by supplying powder T to the preheating flame current R during piercing, combustion efficiency is increased, allowing piercing to be performed in a short time (for example, approximately 10 seconds or less), significantly reducing the operating time.

[0045] Next, after the workpiece W is pierced by supplying powder T to the preheating flame airflow R to form a through hole P, and before the gas cutting process, the powder T continues to be supplied until it passes through the blown-up slag G that has adhered to the upper surface of the workpiece W by piercing. Then, after the blown-up slag G is blown off and peeled off by the powder T and removed, the supply of the powder is stopped and the gas cutting process is started. In this way, in this embodiment, the process of peeling off the blown-up slag G can be performed simultaneously in the piercing process. Therefore, while a normal process would include a preheating process, a piercing process, a process of peeling off the blown-up slag G, a preheating process, and a cutting process, in this embodiment, it is possible to omit a process by simply including a preheating process, a piercing process (including the process of peeling off the blown-up slag G), and a cutting process.

[0046] Furthermore, in this embodiment, the cutting nozzle 1 can automatically spray the powder T, eliminating the need for manual work such as feeding the iron wire into the preheating flame current R, as was done in the past. This means that the need for workers to work on the workpiece W can be eliminated, improving work safety. Moreover, the cutting nozzle 1 of this embodiment can be incorporated into a cutting device and automated, improving work efficiency and quality.

[0047] The cutting nozzle 1 used here includes a gas cutting tip 2 having a cutting oxygen outlet 22 that forms a cutting oxygen supply path 21 and ejects cutting oxygen, and a preheat gas outlet 24 that forms a preheat gas supply path 23 and ejects preheat gas, and a powder feed nozzle 3. The powder feed nozzle 3 includes a powder feed path 31 that extends circumferentially around the outer periphery of the gas cutting tip 2 and supplies powder T, and a powder outlet 32 ​​that ejects powder T toward a preheat flame R formed by preheat gas ejected from the gas cutting tip 2. The powder feed nozzle 3 includes an inner cylinder 35 that fits around the gas cutting tip 2 and an outer cylinder 36 that is positioned on the outer periphery of the inner cylinder 35. The powder outlet 32 ​​is located between the inner cylinder 35 and the outer cylinder 36 and is ring-shaped when viewed in the nozzle axial direction. In this case, the powder outlet 32 ​​of the powder feed nozzle 3 is concentric and ring-shaped, which has the advantage of stabilizing the supply of powder T.

[0048] After the piercing is completed, only the supply of the powder T sprayed from the powder supply nozzle 3 is stopped. Thereafter, the through hole P in the workpiece W created by piercing is used as the cutting starting point, and gas cutting is performed on the workpiece W by the preheating flame current R that is continuously sprayed from the piercing process. In this way, in this embodiment, simply stopping the spraying of powder T after piercing allows the preheating flame current R to continue spraying, making it possible to make an incision of a predetermined shape in the workpiece W. In other words, there is no need to stop the gas cutting tip 2 when switching between piercing and cutting operations, and the cutting operation can be performed efficiently and in a short time.

[0049] In this way, in this embodiment, it is possible to perform cutting continuously immediately after piercing, which has the advantage that there is no need to stop the cutting, damage to the cutting area can be prevented, and the amount of material W that is discarded can be reduced.

[0050] In this embodiment, an example of a powder cutting method is shown in which cutting is started from the through hole P formed by piercing, but the above-mentioned powder cutting method can also be applied to a cutting method in which cutting is done directly from the end face of the workpiece W without piercing.

[0051] The cutting nozzle 1 may be connected to a control unit (not shown). In this case, the control unit separately controls a first control that controls the start and stop of the supply of cutting oxygen and preheating gas ejected from the gas cutting tip 2, and a second control that controls the start and stop of the supply of powder T ejected from the powder ejection nozzle 32. This makes it possible to appropriately adjust the timing and supply time of the powder T according to conditions such as the cutting method and the thickness and material of the workpiece W.

[0052] Furthermore, in the piercing method of this embodiment, the preheating flame current R is covered in a film by the supplied powder T. Therefore, the powder T can be supplied in a state in which it is in uniform contact with the outer periphery of the preheating flame current R in the circumferential direction, and the burning area of ​​the powder T is uniform in cross-sectional view, allowing it to burn evenly across the entire cross section.

[0053] In the piercing method of this embodiment, as shown in FIG. 5, powder T is supplied from the outer periphery of the nozzle of the gas cutting tip 2 toward the preheating flame current R, forming a powder flow Ta that surrounds the preheating flame current R. The powder flow Ta of the powder T extends in a slit-like shape in the direction of the powder T's ejection, forming a non-supply region Tb to which the powder T is not supplied. As a result, the entire preheating flame current R is not completely covered from the outside by the powder flow Ta of the powder T, and a gap of the non-supply region Tb is formed in part of the powder flow Ta. That is, as shown in FIG. 4, slag G blown toward the cutting nozzle 1 during piercing diffuses outward from the powder flow Ta through the slit-like gap of the non-supply region Tb. This prevents the blown slag G from adhering to the nozzle of the gas cutting tip 2 of the cutting nozzle 1, thereby preventing backfire of the gas cutting tip 2.

[0054] In addition, in the cutting nozzle 1 of this embodiment, the powder outlet 32 ​​is provided with a partition rib 33 that divides the nozzle 32 in the circumferential direction around the nozzle axis. The partition rib 33 connects the outer peripheral surface 35a of the inner cylinder 35 with the inner peripheral surface 36a of the outer cylinder 36. This prevents the entire preheating flame stream R from being completely covered from the outside by the powder flow Ta of the powder T, and a gap, a non-supply zone Tb, is formed in part of the powder flow Ta. That is, as shown in FIG. 4 , slag G blown toward the cutting nozzle 1 during piercing diffuses outward from the powder flow Ta through the gap, a non-supply zone Tb. This prevents the blown slag G from adhering to the tip of the gas cutting tip 2 of the cutting nozzle 1, prevents backfire of the gas cutting tip 2, and maintains stable piercing.

[0055] Furthermore, the cutting nozzle 1 of this embodiment is arranged so that the circumferential width of the partition ribs 33 is smaller than the distance between circumferentially adjacent partition ribs 33. In this case, a sufficient amount of powder T can be supplied toward the preheating flame airflow R.

[0056] Furthermore, in the cutting nozzle 1 of this embodiment, the partition ribs 33 are provided at four locations circumferentially at intervals of 90 degrees, so that the blown-up slag G can be uniformly diffused from the gaps in the non-supply area Tb in four directions outward from the powder flow Ta.

[0057] Furthermore, the cutting nozzle 1 of this embodiment is controlled separately from the first control, which controls the start and stop of the supply of cutting oxygen and preheating gas ejected from the gas cutting tip 2, and the second control, which controls the start and stop of the supply of powder T ejected from the powder ejection port 32. Therefore, after piercing, the second control stops only the ejection of powder T, while the preheating flame current R continues to be ejected, allowing the operation of making a cut of a predetermined shape in the workpiece W to be cut.

[0058] Next, examples will be described below that were carried out to verify the effects of the powder cutting method, powder supply nozzle, and powder cutting nozzle according to the above-described embodiment.

[0059] (Example) In this example, a piercing test was conducted on a workpiece W of a predetermined thickness using the cutting nozzle 1 of the above embodiment, and the piercing time was evaluated depending on whether or not powder was used. Figure 7 is a schematic diagram showing the test method, with (a) showing a comparative example without powder supply and (b) showing an example with powder supply. Table 1 shows the test conditions and test results.

[0060] [Table 1]

[0061] The test used two types of fuel gas (flammable gas): hydrocarbon gas (LPG) and hydrogen mixed gas. Piercing was performed on ordinary mild steel workpieces W with thicknesses of 25 mm and 50 mm using an example with powder supply and a comparative example without powder supply, and the piercing preheating time (seconds) and the diameter of the through hole formed by piercing (pierce hole diameter (mm)) were confirmed. Here, the symbol P2(P) in FIG. 7(a) indicates a pierced hole in the comparative example (without powder supply), and the symbol P1(P) in FIG. 7(b) indicates a pierced hole in the example (with powder supply).

[0062] The test conditions, powder supply rate (g / min), opening rate (powder supply port (corresponding to the powder outlet described above)), and nozzle height H (mm) are as shown in Table 1. The nozzle height H from the top surface of the workpiece W to the nozzle was 100 mm in the example (with powder supply) and 10 mm in the comparative example (without powder supply).

[0063] As shown in Table 1, the test results showed that the piercing preheating time (seconds) for the example (with powder supply) was 4 to 8 seconds for a plate thickness of 25 mm and 10 seconds for a plate thickness of 50 mm. On the other hand, the piercing preheating time (seconds) for the comparative example (without powder supply) was 40 to 60 seconds (hydrocarbon gas), 20 to 30 seconds (hydrogen preheating gas), and 70 to 90 seconds (hydrocarbon gas), 60 to 80 seconds (hydrogen preheating gas) for a plate thickness of 50 mm. This demonstrates that the example can significantly reduce the piercing preheating time compared to the comparative example. Furthermore, in the example, increasing the thickness of the workpiece W only slightly increases the piercing preheating time by a few seconds, whereas in the comparative example, the piercing time nearly doubles as the thickness of the workpiece W increases.

[0064] Furthermore, the diameter of the pierced hole in the example (with powder supply) was smaller than that in the comparative example (without powder supply). When the thickness of the workpiece W was 25 mm, the diameter was 8 mm in the example, while it was 12 mm in the comparative example. Furthermore, when the thickness of the workpiece W was 50 mm, the diameter was 12 mm in the example, while it was twice as large, at 24 mm, in the comparative example. This demonstrates that powder supply is effective in reducing the diameter of the pierced hole.

[0065] Furthermore, in the case of the examples, neither the piercing preheating time nor the pierced hole diameter varied depending on the type of gas, so the same effect can be obtained even when using a low-cost gas, for example.

[0066] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design modifications and the like are also included within the scope of the present invention. Furthermore, the components shown in the above-described embodiment and the modified examples shown below can be configured by appropriately combining them.

[0067] For example, in the above-described embodiment, an example of a powder cutting method using cutting nozzle 1 equipped with gas cutting tip 2 and powder supply nozzle 3 has been given, but the present invention is not limited to a powder cutting method in which powder is supplied using cutting nozzle 1. For example, instead of cutting nozzle 1 of this embodiment, it is also possible to provide powder supply means having a function similar to that of powder supply nozzle 3 separately from gas cutting tip 2, and supply powder from the powder supply means to preheating flame airflow R ejected from gas cutting tip 2.

[0068] In addition, in this embodiment, a partition rib 33 (partition portion) is provided at the powder outlet 32 ​​of the powder supply nozzle 3, but this partition rib 33 can be omitted, or the number and position of the partition rib 33 can be changed. For example, like the powder outlet 32A between the outer peripheral surface 35a of the inner tube 35 and the inner peripheral surface 36a of the outer tube 36 of the modified powder supply nozzle 3A shown in Figure 8, it may have a ring-shaped opening around the entire circumference without a partition rib 33 (partition portion).

[0069] Furthermore, the shape and number of each component of the gas cutting tip 2 (cutting oxygen supply channel 21, cutting oxygen nozzle 22, preheating gas supply channel 23, preheating gas nozzle 24, etc.) are not limited to those in the above embodiment. [Industrial Applicability]

[0070] The powder cutting method, powder supply nozzle, and powder cutting nozzle according to the present invention can significantly reduce the time required to cut ordinary mild steel, thereby increasing work efficiency and improving safety. [Explanation of symbols]

[0071] 1 cutting nozzle 2 Gas cutting nozzle 3. 3A powder supply nozzle 21 Cutting oxygen supply channel 22 Cutting oxygen spout 23 Preheating gas supply line 24 Preheating gas outlet 31 Powder supply path 32, 32A Powder nozzle 33 Partition rib (partition part) 34 Nut 35 Inner cylinder 35a Outer surface 36 Outer cylinder (outer wall) 36a Inner surface O Nozzle shaft P through hole R Preheating flame airflow T Powder T3 glow-hot powder Ta powder flow Tb non-supply area W Material to be cut

Claims

1. A powder cutting method for cutting a workpiece made of ordinary mild steel by supplying powder made of iron powder using a gas cutting tip, The gas cutting tip is provided so as to be able to eject cutting oxygen and preheating gas, which is a mixture of preheating oxygen and a flammable gas, toward the material to be cut; supplying the powder toward a preheating flame stream formed by the preheating gas ejected from the gas cutting tip; The preheating gas is ejected from the gas cutting tip, and powder is supplied toward the preheating flame stream formed by the preheating gas ejected from the gas cutting tip, thereby generating red-hot powder in the preheating flame stream, the red-hot powder being arranged around a fixed ejection point of the cutting oxygen stream, and the cutting oxygen is supplied to the red-hot powder around the fixed ejection point to pierce the material to be cut, a gas cutting step of cutting the workpiece by moving the gas cutting tip, continuing from the piercing step, with the through hole machined by the piercing as a cutting start point; A powder cutting method in which, before the gas cutting process, the powder is continuously supplied until the blown-up slag adhering to the upper surface of the workpiece due to the piercing passes through, and after the passage, the supply of the powder is stopped and then the gas cutting process is started.

2. the powder is supplied from the outer periphery of the nozzle of the gas cutting tip toward the preheating flame stream, forming a powder flow surrounding the preheating flame stream; The powder flow of the powder extends in a slit shape in the ejection direction of the powder, forming a non-supply region to which the powder is not supplied.

2. The powder cutting method according to claim 1.

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