JP7738513B2 - Powder cutting method - Google Patents

Description

The present invention relates to a powder cutting method .

Conventionally, when using a gas cutting tip to cut a workpiece made of ordinary mild steel, as shown in Patent Document 1, it is common to preheat the workpiece for a long period of time, such as 1 to 5 minutes, before piercing.

Japanese Unexamined Patent Publication No. 48-41957

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.

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 stream, but this required the skilled technique of the worker to determine the timing of supply, etc., and the quality was not stable. Moreover, when a worker supplies copper wire to the cutting oxygen stream being sprayed into the preheating flame stream above the material to be cut, high-temperature slag exceeding 1500°C is scattered in the vicinity of the worker, so there was a need for further improvements in safety in terms of workability.

The present invention was made in consideration of these circumstances, and aims to provide a powder cutting method, powder supply nozzle, and powder cutting nozzle that can significantly reduce the time required to cut ordinary mild steel, thereby increasing work efficiency and improving safety.

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.

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 stream, forming a powder flow that surrounds the preheating flame stream, and the powder flow extends in a slit shape in the direction of the powder ejection, forming a non-supply area where the powder is not supplied.

In addition, the powder cutting method of the present invention ejects the preheating gas from the gas cutting tip and supplies powder toward the preheating flame stream formed by the preheating gas ejected from the gas cutting tip, generating red-hot powder in the preheating flame stream. The red-hot powder is then positioned around a fixed point of ejection of the cutting oxygen stream, and the cutting oxygen is supplied to the red-hot powder around the fixed point of ejection to pierce the material to be cut.

The powder cutting method according to the present invention also 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. Prior to the gas cutting process, the powder is continuously supplied until it passes through the slag that has adhered to the upper surface of the workpiece due to the piercing. After the slag has passed, the powder supply is stopped, and then the gas cutting process is initiated.

The powder supply nozzle of the present invention is attached to a gas cutting tip that is capable of spraying cutting oxygen and preheating gas, a mixture of preheating oxygen and flammable gas, toward a workpiece made of ordinary mild steel, and is used to perform powder cutting on the workpiece. It is equipped with a powder supply path that extends circumferentially around 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 current made of the preheating gas sprayed from the gas cutting tip.

The powder supply nozzle according to the present invention also has an inner cylinder that fits around the gas cutting tip and an outer cylinder that is positioned on the outer periphery of the inner cylinder, and the powder outlet is positioned between the inner cylinder and the outer cylinder and is formed in a ring shape when viewed in the nozzle axial direction.

In addition, in the powder supply nozzle according to the present invention, the powder outlet is provided with a partition section that divides the outlet in a circumferential direction around the nozzle axis, and the partition section connects the outer peripheral surface of the inner cylinder with the inner peripheral surface of the outer cylinder.

Furthermore, in the powder supply nozzle according to the present invention, the circumferential width dimension of the partition section is smaller than the distance between adjacent partition sections in the circumferential direction.

Furthermore, in the powder supply nozzle according to the present invention, the partitions are provided at four locations spaced 90 degrees apart in the circumferential direction.

Furthermore, the powder supply nozzle according to the present invention is separately controlled by 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.

The powder cutting nozzle according to the present invention also includes the powder supply nozzle described above and the gas cutting tip, which is capable of attaching the powder supply nozzle.

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

1 is a half-longitudinal cross-sectional view showing the overall configuration of a cutting nozzle according to an embodiment of the present invention. 1, and is a front view of the cutting nozzle as seen from the tip end side. FIG. 2 is a view taken along the line X2-X2 in FIG. 1, showing a rear view of the cutting nozzle as seen from behind. FIG. 10 is a diagram showing a state of piercing using a cutting nozzle. 5 is a cross-sectional view taken along line X3-X3 in FIG. 4, showing the powder flow region. 10A to 10D are explanatory diagrams of the powder piercing operation. 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. FIG. 10 is a front view of a cutting nozzle according to a modified example, as viewed from the tip side.

One 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 understand.

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

The gas cutting method according to this embodiment is a method for cutting a workpiece W (see Figures 4 and 7) made of ordinary mild steel using a powder cutting method performed using the cutting nozzle 1 (powder cutting nozzle) shown in Figure 1. That is, the cutting nozzle 1 can be used to pierce the workpiece W or to make cuts from the edge of the workpiece W. With the cutting nozzle 1 of this embodiment, for example, the workpiece W is placed on a substantially horizontal surface on a mounting table (not shown), and one example is shown in which the workpiece W is pierced and then cut using the piercing as the starting point for cutting.

1 to 3, the cutting nozzle 1 includes a gas cutting tip 2 and a powder supply nozzle 3. The cutting nozzle 1 has the powder supply nozzle 3 detachably attached to the outer periphery of the 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.

The gas cutting tip 2 is a tip that is capable of spraying 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.

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 threadedly attached to 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. For example, brass is used as the material for the inner core rod 2A, as it has high thermal conductivity and heat resistance and is also economical in terms of manufacturing costs.

The internal core rod 2A has a cutting oxygen supply passage 21 that extends along the longitudinal nozzle axis O. The cutting oxygen supply passage 21 is connected to the external space at its tip. A cutting oxygen outlet 22 for ejecting cutting oxygen is formed at the tip of the cutting oxygen supply passage 21 on the tip surface 2a of the internal core rod 2A. The cutting oxygen that passes through the cutting oxygen supply passage 21 is ejected forward from the cutting oxygen outlet 22.

The internal core rod 2A also has a preheating gas supply path 23 that extends along the nozzle axis O outside the cutting oxygen supply path 21. The preheating gas supply path 23 is connected to the external space at its tip. At the tip of the preheating gas supply path 23, the tip surface 2a of the internal core rod 2A is formed with multiple slit-shaped preheating gas outlets 24 that extend radially from the cutting oxygen outlet 22 when viewed from the direction of the nozzle axis O. The preheating gas that passes through the preheating gas supply path 23 is ejected forward from the preheating gas outlets 24.

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

Next, the configuration of the powder supply nozzle 3 will be described in detail. As shown in Figures 1 to 3, the powder supply nozzle 3 is provided separately from the gas cutting tip 2. The powder supply nozzle 3 forms a powder supply path 31 that supplies powder T to the outer periphery of the gas cutting tip 2, and has a powder outlet 32 that sprays the powder T.

The powder supply nozzle 3 comprises an inner tube 35 fitted onto the gas cutting tip 2, an outer tube 36 (outer wall) positioned on the outer periphery of the inner tube 35, and a tip stop nut 34 for securing the gas cutting tip 2 inserted inside the inner tube 35. The tip stop nut 34, inner tube 35, and outer tube 36 each have a circular cross-sectional shape. The inner surfaces 34a, 35b of the connecting portions of the tip stop nut 34 and inner tube 35, which connect in the axial direction of the nozzle, are formed to be approximately flush with each other. The gas cutting tip 2 is inserted into the tip stop nut 34 and inner tube 35 from the base end and fitted into them. The tip end of the tip stop nut 34 and the base ends of the inner tube 35 and outer tube 36 are formed with female threads 3a that coaxially connect them. The nozzle retaining nut 34, inner cylinder 35, and outer cylinder 36 are assembled together by tightening the screw 3b shown in Figure 3 into the female threaded portion 3a.

As shown in Figure 1, the shape of the inner surface 35b of the inner cylinder 35 matches the outer surface 2d of the gas cutting tip 2, and the diameter decreases toward the tip. A tapered tip portion 351 is formed on the outer surface 35a of the inner cylinder 35 toward the tip, with the outer diameter decreasing toward the tip.

The outer cylinder 36 has the same length in the nozzle axis direction as the inner cylinder 35. The outer cylinder 36 has a cylindrical base end 361 located on the base end side and extending concentrically in the nozzle axis direction, and a conical tapered portion 362 connected to the tip side of the base end 361. The tapered portion 362 has a shape that tapers toward the tip side.

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 at the base end of the inner cylinder 35. The closing flange 35c is in liquid-tight contact with the inner circumferential surface 36a at the base end 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 at the tip end.

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

As shown in Figure 2, the powder outlet 32 is disposed between the outer peripheral surface 35a of the inner cylinder 35 and the inner peripheral surface 36a of the outer cylinder 36, and is formed in a ring shape when viewed in the nozzle axial direction. Furthermore, the powder outlet 32 is provided with a plurality of (four in this embodiment) partition ribs 33 (partition portions) that divide it in the circumferential direction around the nozzle axis. In other words, the partition ribs 33 are spaced apart at 90° intervals in the circumferential direction.

Multiple partition ribs 33 are arranged at regular intervals around the powder outlet 32, connecting 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 circumferentially at 90° intervals. As shown in FIG. 1, the partition ribs 33 extend from the tips of the inner tube 35 and the outer tube 36 toward their 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.

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

Next, we will explain the operations involved in carrying out the piercing method for piercing a workpiece W made of ordinary mild steel using the cutting nozzle 1, and the 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 this embodiment described above.

First, as shown in FIG. 2, the cutting nozzle 1 to be used is an integrated gas cutting tip 2 and a powder supply nozzle 3 attached thereto.
2 and 4, preheating gas, which is a mixture of preheating oxygen and a combustible gas, is supplied to the preheating gas supply passage 23 of the gas cutting tip 2 of the cutting nozzle 1, and this preheating gas is ejected to the outside from the preheating gas outlet 24 to generate a preheating flame. At the same time, cutting oxygen is supplied to the cutting oxygen supply passage 21 and ejected from the cutting oxygen outlet 22. Furthermore, in the powder supply nozzle 3, powder T is supplied to the powder supply passage 31 and ejected from the powder outlet 32. At this time, the powder T ejected from the powder outlet 32 is supplied toward the preheating flame airflow R made of the 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.

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 that 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 form of a slit.

The ejected powder T is supplied to the preheated flame airflow R inside the powder flow Ta, where it is sufficiently heated and melted before being ejected toward the workpiece W, which is made of ordinary mild steel. Moreover, the powder T does not scatter outward and is lost, allowing most of the powder T to be burned efficiently.

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 current R, which is made up of the preheating gas ejected from the gas cutting tip 2. This generates red-hot powder T3 in the preheating flame current R. In Figures 6(a) to 6(d), reference symbol T1 indicates powder immediately after ejection, reference symbol T2 indicates powder in the process of becoming red-hot, and reference symbol T3 indicates red-hot powder. The red-hot powder T3 is then positioned around the fixed ejection point Va of the cutting oxygen current 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.

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 rate of the powder T increases, the exothermic reaction becomes stronger, the combustion efficiency increases, and the base material of the workpiece W is melted, while 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.

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 completed in a short time (for example, approximately 10 seconds or less), significantly reducing the operating time.

Next, the workpiece W is pierced by supplying powder T to the preheating flame airflow R to form a through hole P, and then, 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 within 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, the process includes a preheating process, a piercing process (including the process of peeling off the blown-up slag G), and a cutting process, making it possible to omit a process.

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 airflow R, as was previously required. This means that the operator no longer needs to perform work on the workpiece W, thereby improving work safety. Moreover, the cutting nozzle 1 of this embodiment can be incorporated into cutting equipment and automated, improving work efficiency and quality.

The cutting nozzle 1 used here comprises 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 comprises 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 the preheat flame airflow R composed of preheat gas ejected from the gas cutting tip 2. The nozzle has 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 from 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.

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 ejected from the piercing process. In this manner, in this embodiment, simply stopping the ejection of powder T after piercing allows the preheating flame current R to continue ejecting, 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.

In this way, in this embodiment, it is possible to continue cutting continuously after piercing. This means there is no need to stop, damage to the cutting area can be prevented, and there are advantages in reducing the amount of material W to be cut that is discarded.

In this embodiment, an example of a powder cutting method has been shown in which cutting is started from a through hole P formed by piercing. However, the above-described powder cutting method can also be applied to cutting methods in which cutting is done directly from the end face of the workpiece W without piercing.

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 powder T according to conditions such as the cutting method and the thickness and material of the workpiece W.

Furthermore, in the piercing method of this embodiment, the preheating flame current R is covered in a film-like manner by the supplied powder T. As a result, the powder T can be supplied in a state where it is in uniform contact with the outer periphery of the preheating flame current R in the circumferential direction, and there is no unevenness in the combustion area of the powder T when viewed in cross section, allowing it to burn evenly across the entire cross section.

In addition, 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 extends in a slit-like shape in the direction of the powder T's ejection, forming a non-supply region Tb where 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 powder T, and a gap in the non-supply region Tb is formed in part of the powder flow Ta. That is, as shown in FIG. 4, slag G that is blown toward the cutting nozzle 1 during piercing diffuses outward from the powder flow Ta through the slit-like gap in the non-supply region Tb. This prevents slag G from adhering to the tip of the gas cutting tip 2 of the cutting nozzle 1, preventing backfire of the gas cutting tip 2.

In addition, in the cutting nozzle 1 of this embodiment, the powder outlet 32 is equipped with a partition rib 33 that divides the area circumferentially around the nozzle axis. The partition rib 33 connects the outer surface 35a of the inner cylinder 35 with the inner surface 36a of the outer cylinder 36. This prevents the entire preheating flame current R from being completely covered from the outside by the powder flow Ta of powder T, and creates a gap in the non-supply zone Tb in part of the powder flow Ta. That is, as shown in FIG. 4, blown-up slag G that is scattered toward the cutting nozzle 1 during piercing diffuses outward from the powder flow Ta through the gap in the non-supply zone Tb. This prevents blown-up 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.

In addition, 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 adjacent partition ribs 33 in the circumferential direction. In this case, a sufficient amount of powder T can be supplied toward the preheating flame airflow R.

In addition, the cutting nozzle 1 of this embodiment has four partition ribs 33 arranged at 90-degree intervals around the circumference, allowing the blown-up slag G to be uniformly dispersed from the gaps in the non-supply area Tb in four directions outward from the powder flow Ta.

In addition, the cutting nozzle 1 of this embodiment is controlled separately by 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 port 32. Therefore, after piercing, the second control stops only the ejection of powder T, while the preheating flame airflow R continues to be ejected, allowing the operation of making a cut of the desired shape into the workpiece W.

Next, we will explain examples conducted to demonstrate the effectiveness of the powder cutting method, powder supply nozzle, and powder cutting nozzle according to the above-mentioned embodiments.

(Example)
In this example, a piercing test was conducted on a workpiece W having 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 in which no powder was supplied, and (b) showing an example in which powder was supplied. Table 1 shows the test conditions and test results.

In the test, two types of fuel gas (flammable gas) were used: hydrocarbon gas (LPG) and hydrogen mixed gas. Piercing was performed on ordinary mild steel workpieces W having thicknesses of 25 mm and 50 mm using the example with powder supply and the 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).

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).

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) for a plate thickness of 25 mm, 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.

Furthermore, the pierce hole diameter in the Example (with powder supply) is smaller than in the Comparative Example (without powder supply). When the thickness of the workpiece W was 25 mm, it was 8 mm in the Example and 12 mm in the Comparative Example. Furthermore, when the thickness of the workpiece W was 50 mm, it was 12 mm in the Example and doubled to 24 mm in the Comparative Example. This demonstrates that powder supply is efficient in reducing the pierce hole diameter.

Furthermore, in the case of the examples, no variation was observed in either the piercing preheating time or the pierced hole diameter depending on the type of gas. Therefore, the same effect can be obtained even if a low-cost gas is used, for example.

Although an embodiment of the present invention has 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 in any suitable combination.

For example, in the above-described embodiment, a powder cutting method using a cutting nozzle 1 equipped with a gas cutting tip 2 and a powder supply nozzle 3 was exemplified, but the present invention is not limited to a powder cutting method in which powder is supplied using the cutting nozzle 1. For example, instead of the cutting nozzle 1 of this embodiment, a powder supply means having a function similar to the powder supply nozzle 3 can be provided separately from the gas cutting tip 2, and powder can be supplied from the powder supply means to the preheating flame airflow R ejected from the gas cutting tip 2.

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 cylinder 35 and the inner peripheral surface 36a of the outer cylinder 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).

Furthermore, the shape and quantity 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.

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

1 Cutting nozzle 2 Gas cutting tip 3, 3A Powder supply nozzle 21 Cutting oxygen supply channel 22 Cutting oxygen nozzle 23 Preheating gas supply channel 24 Preheating gas nozzle 31 Powder supply channel 32, 32A Powder nozzle 33 Partition rib (partition section)
34 Nut 35 Inner cylinder 35a Outer peripheral surface 36 Outer cylinder (outer peripheral wall)
36a Inner peripheral surface O Nozzle axis P Through hole R Preheating flame airflow T Powder T3 Red-hot powder Ta Powder flow Tb Non-supply area W Material to be cut

Claims (2)

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 . 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.