Torch cutting method for angle steel, channel steel, and square steel pipes
The torch cutting method for shaped steel adjusts the torch axis inclination to reduce speed differentials, addressing defects in existing cutting methods by ensuring consistent speed across inner and outer surfaces, resulting in a smoother cut.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- DAITO SEIKI CO LTD
- Filing Date
- 2026-02-17
- Publication Date
- 2026-06-23
AI Technical Summary
Existing methods for cutting shaped steel such as channel steel, grooved steel, and angle steel pipes result in defects like notches and gouges due to significant differences in cutting speed between the inner and outer surfaces of the corner parts, which are not adequately addressed by existing techniques.
A torch cutting method that adjusts the inclination angle of the torch axis proportionally during the cutting process, ensuring the torch moves in a manner that reduces the speed differential between the inner and outer surfaces, particularly at corner sections, by incrementally changing the torch's inclination angle in specific patterns.
This method effectively suppresses the difference in cutting speed between the inner and outer surfaces, thereby minimizing defects on the cutting surface, providing a smoother and more precise cut.
Smart Images
Figure 0007878793000001_ABST
Abstract
Description
Technical Field
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[0001] The present invention relates to a method for torch cutting of channel steel, grooved steel, and angle steel pipes.
Background Art
[0002] Conventionally, gas torches, plasma torches, laser torches, etc. have been used for cutting shaped steel such as channel steel, grooved steel, and angle steel pipes. When cutting the corner part of the shaped steel with these torches, defects such as notches and gouges may occur on the cutting surface due to the difference in cutting speed between the inner and outer surfaces of the corner part.
[0003] Therefore, a technique for suppressing the difference in cutting speed between the inner and outer surfaces of the corner part has been proposed, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 7-132371). The technique of this Patent Document 1 controls the torch posture so that the torch axis passes through an arbitrary point G that is farther from the corner part than the center of curvature of the arc part (fillet part) of the inner surface of the corner part.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] However, since the technique of Patent Document 1 controls the torch axis to pass through point G, although the difference in cutting speed between the inner and outer surfaces of the corner part can be reduced more than before, the difference in cutting speed between the inner and outer surfaces is still quite large. Therefore, there is room for improving the effect of suppressing the occurrence of defects on the cutting surface.
[0006] Therefore, an object of the present invention is to further reduce the difference in cutting speed between the inner and outer surfaces of the corner part of channel steel, grooved steel, and angle steel pipes, thereby further suppressing the occurrence of defects on the cutting surface. [Means for solving the problem]
[0007] The torch cutting method for angle steel according to the present invention is a method for cutting angle steel, in which a pair of flange portions are connected at a corner portion, with a torch in a direction perpendicular to the longitudinal direction of the angle steel, characterized in that, when the torch is moved in the order of the tip of one of the flange portions of the angle steel, the torch is moved from the tip of one of the flange portions, the corner portion, and the other flange portion, the inclination angle of the axis of the torch in the direction of torch movement is increased proportionally with the torch movement from the tip of one of the flange portions to the corner of the outer surface of the corner portion, and the inclination angle of the axis of the torch in the direction opposite to the direction of torch movement is decreased proportionally with the torch movement from the corner of the outer surface of the corner portion to the tip of the other flange portion.
[0008] The torch cutting method for channel steel according to the present invention is a method for cutting channel steel, in which a pair of flange portions are connected by a web portion and a pair of corner portions at both ends of the web portion, with a torch in a direction perpendicular to the longitudinal direction of the channel steel, wherein the torch is moved in the order of the tip of one of the flange portions of the channel steel, the one flange portion, the one corner portion, the web portion, the other corner portion, and the other flange portion, and the inclination angle of the axis of the torch in the direction of torch movement is proportional to the torch movement as the torch moves, from the tip of one flange portion to the corner of the outer surface of one corner portion. The torch is characterized by increasing the angle of inclination of the torch axis in the direction opposite to the direction of torch movement as the torch moves, from the corner of the outer surface of one of the corner portions to the center of the web portion, increasing the angle of inclination of the torch axis in the direction of torch movement as the torch moves, from the center of the web portion to the corner of the outer surface of the other corner portion, and decreasing the angle of inclination of the torch axis in the direction opposite to the direction of torch movement as the torch moves, from the corner of the outer surface of the other corner portion to the tip of the other flange portion.
[0009] The torch cutting method for a square steel pipe according to the present invention is a method for cutting a square steel pipe, in which four web portions are connected at a corner portion, with a torch in a direction perpendicular to the longitudinal direction of the square steel pipe, and is characterized by comprising: a first step of moving the torch from the center of the cutting direction of any one of the four web portions of the square steel pipe to the center of the cutting direction of another adjacent web portion via the corner portion, and increasing the inclination angle of the axis of the torch in the direction of torch movement proportionally as the torch moves, from the middle of the web portion to the center of the outer surface of the corner portion; and a second step of decreasing the inclination angle of the axis of the torch in the direction opposite to the direction of torch movement proportionally as the torch moves, from the center of the outer surface of the corner portion to the center of the adjacent web portion. [Effects of the Invention]
[0010] According to the present invention, the difference in cutting speed between the inner and outer surfaces of the corner sections of angle steel, channel steel, and square steel pipes can be suppressed, thereby preventing defects from occurring on the cut surface. [Brief explanation of the drawing]
[0011] [Figure 1] (a) is a cross-sectional view and (b) is an enlarged cross-sectional view of a key part showing a torch cutting method for angle steel according to one embodiment of the present invention. [Figure 2] (a) is a cross-sectional view and (b) is an enlarged cross-sectional view of a key part showing a torch cutting method for channel steel according to one embodiment of the present invention. [Figure 3] (a) a cross-sectional view of the first step, (b) a cross-sectional view of the second step, and (c)-(f) enlarged cross-sectional views of each corner section of a torch cutting method for square steel pipes according to one embodiment of the present invention. [Figure 4] Figures (a)-(e) are explanatory diagrams of an embodiment in which angle steel is torch-cut in the inclined direction. [Figure 5] This is an explanatory diagram of an embodiment for torch cutting of channel steel in an inclined direction. [Figure 6] This is an explanatory diagram of an embodiment for torch cutting of a square steel pipe in an inclined direction. [Modes for carrying out the invention]
[0012] Hereinafter, with reference to the drawings, a method for cutting channel steel, angle steel, and square steel pipes with a torch according to an embodiment of the present invention will be described.
[0013] ● Torch cutting of angle steel Figures 1(a) and 1(b) are a cross-sectional view and an enlarged cross-sectional view of the main part showing the torch cutting method of angle steel 10. As shown in Figure 1(a), the angle steel 10 has a pair of flange portions 11 and 12. The pair of flange portions 11 and 12 are connected at a right angle at the corner.
[0014] A right-angle corner 13 is formed on the outer surface of the corner. In addition, an arc-shaped fillet 14 is formed on the inner surface of the corner. The fillet 14 is formed in the shape of an arc with a predetermined radius centered on the center of curvature O.
[0015] The following describes a method for cutting angle steel 10 with a torch T perpendicular to its longitudinal direction. Various torches, such as gas torches, plasma torches, and laser torches, can be used for cutting.
[0016] As shown in Figure 1(a), the torch T is moved starting from the tip 11a of one flange portion 11 of the angle steel 10, in the order of one flange portion 11, the corner portion 13 of the corner section, and the other flange portion 12. At this time, the inclination angle of the axis of the torch T in the direction of torch movement is increased proportionally as the torch moves, from the tip 11a of one flange portion 11 to the corner portion 13 of the outer surface of the corner section.
[0017] Further, from the corner 13 of the outer surface of the corner portion to the tip end portion 12a of the other flange portion 12, the inclination angle of the axis of the torch T in the direction opposite to the torch movement direction is decreased proportionally with the torch movement. Specifically, as shown in Fig. 1(b), the torch movement locus on the outer surface of one flange portion 11 of the angle steel 10 is divided into a plurality of spans at a predetermined pitch. The torch movement locus on the outer surface of the other flange portion 12 is also divided into a plurality of spans at the same predetermined pitch.
[0018] When cutting one flange portion 11 from the tip end portion 11a to the corner 13, the inclination angle of the axis of the torch T in the torch movement direction in each of the divided spans is increased proportionally with each torch movement between the plurality of spans. Further, when cutting the other flange portion 12 from the corner 13 to the tip end portion 12a, the inclination angle of the axis of the torch T in the direction opposite to the torch movement direction in each of the divided spans is decreased proportionally with each torch movement between the plurality of spans. "Proportionally" means changing the inclination angle of the axis of the torch T in proportion to the movement amount of the torch T.
[0019] The predetermined pitch for dividing the flange portions 11 and 12 into a plurality of spans can be set to a predetermined pitch between, for example, 1 mm and 5 mm. When the axis of the torch T reaches the corner 13 of the outer surface of the corner portion, it can be set so that the axis of the torch T passes through the center of curvature O of the fillet portion 14 formed on the inner surface of the corner portion.
[0020] However, it is not essential for the axis of the torch T to pass through the center of curvature O. Depending on the shape, size, etc. of the corner portion of the angle steel 10, it is also possible to set it so that the axis of the torch T does not pass through the center of curvature O when it reaches the corner 13. Thus, by changing the inclination angle θ of the axis of the torch T moment by moment at all positions of the angle steel 10 cut by the torch T (θ1 - θ5), the difference in the cutting speed between the inner and outer surfaces of the corner portion can be suppressed more than the technique of Patent Document 1, and the occurrence of defects on the cut surface can be suppressed.
[0021] ● Torch cutting of channel steel Figs. 2(a) and (b) are a cross-sectional view and an enlarged cross-sectional view of the main part showing a torch cutting method for channel steel 20. The channel steel 20 has a pair of left and right flange portions 21 and 22. The pair of flange portions 21 and 22 are connected to a web portion 23 and a pair of corner portions at both ends of the web portion 23.
[0022] Right-angle corners 24 and 25 are formed on the outer surfaces of a pair of corner sections. In addition, arc-shaped fillet sections 26 and 27 are formed on the inner surfaces of a pair of corner sections. The fillet sections 26 and 27 are formed in the shape of an arc with a predetermined radius centered on the center of curvature O.
[0023] The following describes a method for cutting the channel steel 20 with a torch T in a direction perpendicular to its longitudinal direction. As shown in Figure 2(a), the torch T is moved starting from the tip 21a of one flange portion 21 of the channel steel 20, then along the one flange portion 21, the corner portion 24, and the other flange portion 22.
[0024] In this process, the inclination angle of the axis of the torch T in the direction of torch movement is increased proportionally as the torch moves, from the tip 21a of one flange portion 21 to the corner 24 of the outer surface of one corner portion. Next, the inclination angle of the axis of the torch T in the direction opposite to the direction of torch movement is decreased proportionally as the torch moves, from the corner 24 of the outer surface of one corner portion to the central portion 23a of the web portion 23.
[0025] Here, "center" refers to the center of the web portion 23 in the cutting direction or the center in the width direction. However, the "center" does not need to be precisely the center in the cutting direction or the center in the width direction in terms of dimensions. In particular, in areas where the thickness change of the web portion 23 is zero or very small, it is possible to set an allowable width of a few millimeters to the left or right of the exact "center".
[0026] Next, the inclination angle of the axis of the torch T in the direction of torch movement is increased proportionally as the torch moves, from the central part 23a of the web part 23 to the corner 25 of the outer surface of the other corner part. Next, the inclination angle of the axis of the torch T in the direction opposite to the direction of torch movement is decreased proportionally as the torch moves, from the corner 25 of the outer surface of the other corner part to the tip 22a of the other flange part 22.
[0027] More specifically, as shown in Figure 2(b), the torch movement trajectory on the outer surface of the flange portion 21 of the channel steel 20 is divided into multiple spans at a predetermined pitch. Similarly, the torch movement trajectory on the outer surface of the opposite flange portion 22 and web portion 23 is also divided into multiple spans at a predetermined pitch.
[0028] The inclination angle of the axis of the torch T in each divided span is proportionally increased or decreased each time the torch moves between multiple spans. That is, from the tip 21a of one flange portion 21 to the corner 24 of the outer surface of one corner portion, the inclination angle of the axis of the torch T in each divided span in the direction of torch movement is proportionally increased each time the torch moves between multiple spans.
[0029] Furthermore, the inclination angle of the axis of the torch T in the direction opposite to the torch movement direction in each divided span is proportionally reduced each time the torch moves between multiple spans, from the corner 24 on the outer surface of one corner section to the central part 23a of the web section 23. Furthermore, the inclination angle of the axis of the torch T in the direction of torch movement in each divided span is proportionally increased each time the torch moves between multiple spans, from the central part 23a of the web section 23 to the corner 25 on the outer surface of the other corner section. Furthermore, the inclination angle of the axis of the torch T in the direction opposite to the torch movement direction in each divided span is proportionally reduced each time the torch moves between multiple spans, from the corner 25 on the outer surface of the other corner section to the tip 22a of the other flange section 22.
[0030] The predetermined pitch for dividing the flange portions 21, 22 and the web portion 23 into multiple spans can be set to a predetermined pitch between 1 mm and 5 mm, for example. When the axis of the torch T reaches the corners 24, 25 on the outer surface of the corner portion, the axis of the torch T can be set to pass through the center of curvature O of the fillet portions 26, 27 formed on the inner surface of the corner portion.
[0031] However, it is not essential that the axis of the torch T passes through the center of curvature O. Depending on the shape and size of the corner portion of the channel steel 20, it is possible to set the axis of the torch T so that it does not pass through the center of curvature O when it reaches the corner portions 24 and 25, as shown in Figures 2(a) and (b). In this way, by constantly changing the inclination angle θ of the axis of the torch T at all positions of the channel steel 20 being cut by the torch T, the difference in cutting speed between the inner and outer surfaces of the corner portion can be suppressed more than the technology in Patent Document 1, and the occurrence of defects in the cut surface can be suppressed.
[0032] ● Torch cutting of square steel pipes Figures 3(a) and 3(b) are cross-sectional views of the square steel pipe 30. The square steel pipe 30 consists of four web sections 31-34 on the top, bottom, left, and right sides, connected via four corner sections. The outer and inner surfaces of each corner section are formed in an arc shape. The inner surfaces of each corner section constitute fillet sections 35-38.
[0033] When cutting this square steel pipe 30 with a torch perpendicular to its longitudinal direction, the right and left sides of the center line S of the square steel pipe 30 are cut in separate steps, as shown in Figures 3(a) and (b). That is, in the first step (a), the torch T is moved clockwise from the first position I to the second position II on the opposite side. This allows the right half of the square steel pipe 30 to be cut.
[0034] Subsequently, in the second step of (b), the torch T is moved clockwise from the third position III to the fourth position IV on the opposite side. This allows the left half of the square steel pipe 30 to be cut.
[0035] Figures 3B(c)-(f) show the torch movement trajectory of the corner section of the square steel pipe 30, divided into multiple spans at a predetermined pitch L. The four web sections 31-34 are similarly divided into multiple spans at a predetermined pitch L.
[0036] If the radius of curvature R of the outer surface of the corner section is 18 mm, and the number of divisions of multiple spans is, for example, 10, then the central angle of one pitch is 9°. Therefore, the predetermined pitch L = 18 tan 9° = 2.85 mm. The inclination angle of the axis of the torch T is constant for the span of one pitch (2.85 mm). When the axis of the torch T moves to the next pitch, the inclination angle of the axis of the torch T is changed.
[0037] When the starting point for torch cutting is the center of the web sections 31 and 33, the inclination angle of the torch T's axis is zero at that starting point. That is, at the starting point for torch cutting, the axis of the torch T is perpendicular to the width direction of the web sections 31 and 33. Furthermore, within one pitch (2.85 mm) including the starting point for torch cutting, the axis of the torch T is perpendicular to the longitudinal direction of the web sections 31 and 33.
[0038] When the axis of the torch T moves from the center of the web sections 31 and 33 to the next pitch (2.85 mm), the inclination angle of the axis of the torch T in the direction of torch movement is increased proportionally with the torch movement. If the inclination angle of the axis of the torch T when it reaches the center of the outer surface of the corner section is, for example, 45°, then the inclination angle of the axis of the torch T in the direction of torch movement can be increased proportionally from 0° to 45° in increments of 1 pitch (2.85 mm) from the starting point of torch cutting until the axis of the torch T reaches the center of the outer surface of the corner section. This is called the first step.
[0039] Next, the inclination angle of the axis of the torch T in the direction opposite to the direction of torch movement in each divided span is proportionally reduced each time the torch moves between multiple spans, from the center of the outer surface of the corner section to the center of an adjacent web section. This is called the second step.
[0040] Here, "proportional increase" and "proportional decrease" include both cases where the angle increases or decreases by a constant angle for each pitch, and cases where the inclination angle increases or decreases exponentially for each pitch. Depending on the cutting conditions, it is possible to choose either to increase or decrease the angle by a constant angle for each pitch, or to increase or decrease the inclination angle exponentially for each pitch.
[0041] The torch movement trajectory on the outer surface of the square steel pipe 30 can be divided into multiple spans at predetermined pitches between 1 mm and 5 mm, for example. When the axis of the torch T reaches the center of the outer surface of the corner, the axis of the torch T can be set to pass through the center of curvature O of the outer surface of the corner.
[0042] However, it is not essential that the axis of the torch T passes through the center of curvature O. Depending on the shape and size of the corner of the square steel pipe 30, it is possible to set the axis of the torch T so that it does not pass through the center of curvature O when it reaches the center of the outer surface of the corner. In this way, by constantly changing the inclination angle θ of the axis of the torch T at all positions of the square steel pipe 30 being cut by the torch T, the difference in cutting speed between the inner and outer surfaces of the corner can be suppressed more than the technology in Patent Document 1, and the occurrence of defects in the cut surface can be suppressed.
[0043] ● Regarding the difference in cutting speed between the inner and outer surfaces of the corners From the starting point of the torch cut to the entrance of the corner section, the torch T is moved in a straight line, so the cutting thickness of the torch T is almost constant. The same is true when the torch T is moved in a straight line from the exit of the corner section to the center of the cutting direction of another adjacent web section. Therefore, when the cutting thickness is almost constant and the torch T is moved in a straight line in this way, no difference in cutting speed occurs on the inner and outer surfaces of the web sections 31-34, even if the torch axis is not tilted at all.
[0044] However, when torch T cuts a corner, a difference in cutting speed inevitably occurs between the inner and outer surfaces of the corner. This difference in cutting speed between the inner and outer surfaces of the corner is also true for angle steel 10 and channel steel 20.
[0045] In the technology described in Patent Document 1 (Japanese Patent Publication No. 7-132371), the axis of the torch begins to tilt in the direction of torch movement when the torch approaches the entrance of the corner (steps 0010, 0011, and 0026). This slows down the change in the tilt of the torch axis, suppressing the difference in cutting speed between the inner and outer surfaces of the corner and thereby suppressing defects in the cut surface.
[0046] However, even if the torch axis is tilted slightly before it enters the corner, it is insufficient to sufficiently reduce the difference in cutting speed between the inner and outer surfaces of the corner. Therefore, in this embodiment, the torch axis is tilted at one-pitch intervals from the starting point of torch cutting.
[0047] In angle steel 10 and channel steel 20, the torch axis begins to tilt at one pitch intervals from the tip portions 11a and 21a of the flange portions 11 and 21. In square steel pipe 30, the torch axis begins to tilt at one pitch intervals from the center of the web portions 31 and 33.
[0048] By starting to tilt the torch axis early in this way, the difference in cutting speed between the inner and outer surfaces of the corner can be sufficiently reduced. As a result, defects in the cut surface can be suppressed even more effectively than in the technique described in Patent Document 1 (Japanese Patent Publication No. 7-132371).
[0049] ●Angle cut of angle steel Figures 4(a)-(e) are explanatory diagrams of an embodiment in which the angle steel 10 is torch-cut in an inclined direction. That is, as shown in Figure 4(a), one flange portion 12 is torch-cut perpendicular to the longitudinal direction of the angle steel 10, while the other flange portion 11 is torch-cut in an inclined direction relative to the longitudinal direction of the angle steel 10.
[0050] During torch cutting, the axis of the torch T is aligned with the second plane S2 in Figure 4(e). This second plane S2 includes the cutting surface 12b and is perpendicular to the other flange portion 11.
[0051] Torch cutting begins at the tip 11a of the other flange portion 11 of the angle steel 10, and the torch T is moved in the following order: the cut surface 11b of the other flange portion 11, the corner portion, and the cut surface 12b of the other flange portion 12. During this process, the inclination angle of the axis of the torch T in the direction of torch movement is increased proportionally as the torch moves, from the tip 11a of the other flange portion 11 through the cut surface 11b to the corner portion 13 of the outer surface of the corner portion. This is called the first step.
[0052] As the axis of the torch T moves from the corner 13 on the outer surface of the corner portion through the cut surface 12b of one flange portion 12 to the tip portion 12a, the inclination angle of the axis of the torch T in the direction opposite to the direction of torch movement is decreased proportionally as the torch moves. This is called the second step.
[0053] At the start of the second step, that is, before the axis of the torch T reaches the corner 13 on the outer surface of the corner (the beginning of the cut surface 12b), the axis of the torch T is tilted until it coincides with the first plane S1 that bisects the inner angle of the corner at 45°. By proceeding with the second step from this state where the axis of the torch T is tilted at 45°, the tip of the torch T can be brought close enough to the corner of the angle steel 10 to obtain a good cut surface, and interference between the tip of the torch T and the corner 13 can be avoided.
[0054] ● Diagonal cutting of channel steel Figure 5 is an explanatory diagram of an embodiment in which a channel steel 20 is torch-cut in an inclined direction. As shown in Figure 5, the pair of flange portions 21 and 22 of the channel steel 20, which are connected to the web portion 23 by a pair of corner portions 24 and 25 at both ends of the web portion 23, are cut with a torch in a direction perpendicular to the longitudinal direction of the channel steel 20. In addition, the web portion 23 is cut with a torch in an inclined direction relative to the longitudinal direction of the channel steel 20.
[0055] During torch cutting, the axis of the torch T is aligned with the second plane S2 in Figure 5. The second plane S2 includes the cutting surface 23b of the web portion 23 and is a plane perpendicular to the web portion 23.
[0056] Starting from the tip 22a of one flange portion 22 of the channel steel 20, the torch T is moved in the following order: the flange portion 22, one corner portion 25, the web portion 23, the other corner portion 24, and the other flange portion 21. During this process, the inclination angle of the axis of the torch T in the direction of torch movement is increased proportionally as the torch moves, from the tip 22a of one flange portion 22 to one corner portion 25. This is called the first step.
[0057] When the first step ends at corner 25, the axis of the torch T is aligned with the first plane S1 in Figure 5. This first plane S1 is the plane that bisects the interior angle of corner 25 by 45°.
[0058] As the axis of the torch t moves from one corner 25 to the center of the web 23, the inclination angle of the axis of the torch T in the direction opposite to the direction of torch movement is decreased proportionally as the torch moves. This is called the second step.
[0059] As the axis of the torch T moves from the center of the web portion 23 to the other corner portion 24, the inclination angle of the axis of the torch T in the direction of torch movement is increased proportionally with the torch movement. This is called the third step. When the third step ends at corner portion 24, the axis of the torch T is aligned with a plane that bisects the interior angle of corner portion 24 by 45°.
[0060] As the axis of the torch T moves from the other corner 24 to the tip 21a of the other flange 21, the inclination angle of the axis of the torch T in the direction opposite to the direction of torch movement is decreased proportionally as the torch moves. This is called the fourth step.
[0061] At the start of the second and fourth steps, that is, before the axis of the torch T reaches the corners 25 and 24 on the outer surface of the corner section (the beginning of the cut surfaces 23b and 21b), the axis of the torch T is tilted until it coincides with the first plane S1 that bisects the inner angle of the corner section by 45°. By proceeding with the second and fourth steps from this state in which the axis of the torch T is tilted at 45°, the tip of the torch T can be brought close enough to the corner section of the channel steel 20 to obtain a good cut surface, and interference between the tip of the torch T and the corners 25 and 24 can be avoided.
[0062] ● Diagonal cutting of square steel pipes Figure 6 is an explanatory diagram of an embodiment in which a square steel pipe 30 is torch-cut in an inclined direction. As shown in Figure 6, a pair of opposing web portions 32 and 34 of a square steel pipe 30, in which four web portions 31-34 are connected at the corner portions, are cut with a torch T along the cutting surfaces 32b and 34b perpendicular to the longitudinal direction of the square steel pipe 30. In addition, another pair of opposing web portions 31 and 33 are cut with a torch T along the cutting surfaces 31b and 33b that are inclined with respect to the longitudinal direction of the square steel pipe 30.
[0063] While cutting the four web portions 31-34, the axis of the torch T is aligned with the second plane S2 in Figure 6. The second plane S2 is a plane perpendicular to the web portions 31 and 33, and the cutting surfaces 31b and 33b in the inclined direction of the web portions 31 and 33 are included in the second plane S2. In this embodiment, the inclination direction of the cutting surfaces 31b and 33b is described as 45°, but the inclination direction is not limited to 45°.
[0064] Starting from the center of the cutting direction of any one of the four web sections 31-34 of the square steel pipe 30, the torch T is moved through the corner section to the center of the cutting direction of the adjacent web section. By repeating this four times, the square steel pipe 30 can be cut.
[0065] The inclination angle of the torch axis in the direction of torch movement is increased proportionally as the torch moves, from the center of the cutting direction of the web portion 31-34 to the center of the outer surface of the corner portion. This is called the first step.
[0066] As the axis of the torch T moves from the center of the outer surface of the corner to the center of the cutting direction of the adjacent web, the inclination angle of the axis of the torch T in the direction opposite to the direction of torch movement is decreased proportionally with the torch movement. This is called the second step.
[0067] At the start of the second step, that is, before the axis of the torch T reaches the center of the outer surface of the corner section, the axis of the torch T is tilted until it coincides with the first plane S1 that bisects the inner angle of the corner section at 45°. By proceeding with the second step from this state where the axis of the torch T is tilted at 45°, the tip of the torch T can be brought close enough to the corner section of the square steel pipe 30 to obtain a good cut surface, and interference between the tip of the torch T and the corner section can be avoided.
[0068] ●Summary Although several embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications are possible based on the technical idea described in the claims. [Explanation of Symbols]
[0069] 10: Angle steel 11: Flange section 11a: Tip section 12: Flange section 12a: Tip 13: Corner 14: Fillet section 20: Channel steel 21: Flange section 21a: Tip section 22: Flange section 22a: Tip section 23: Web section 24, 25: Corner section 26: Fillet section 30: Square steel pipe 31-34: Web section 35-38: Fillet section L: predetermined pitch O: center of curvature R: Radius of curvature T: Torch
Claims
1. A torch cutting method for angle steel, wherein an angle steel in which a pair of flange portions are connected at a corner portion is cut with a torch in a direction perpendicular to the longitudinal direction of the angle steel, When moving the torch starting from the tip of one flange portion of the angle steel, in the order of that flange portion, the corner portion, and the other flange portion, The axis of the torch is positioned such that the inclination angle of the torch axis in the direction of torch movement increases proportionally with torch movement, from the tip of one of the flange portions to the corner of the outer surface of the corner portion. The axis of the torch, from the corner of the outer surface of the corner portion to the tip of the other flange portion, has an inclination angle of the axis of the torch in the direction opposite to the direction of torch movement that decreases proportionally as the torch moves. A torch cutting method for angle steel, characterized by the following features.
2. The torch movement trajectory on the outer surface of the angle steel is divided into multiple spans at a predetermined pitch, The axis of the torch extends from the tip of one of the flange portions to the corner of the outer surface of the corner portion, and the inclination angle of the torch axis in the direction of torch movement in each of the divided spans is increased proportionally with each torch movement between the multiple spans. The axis of the torch, from the corner of the outer surface of the corner portion to the tip of the other flange portion, is inclined in the direction opposite to the direction of torch movement in each of the divided spans, and this is proportionally reduced each time the torch moves between the multiple spans. The torch cutting method for angle steel according to feature 1.
3. The torch cutting method for angle steel according to claim 2, characterized in that the torch movement trajectory on the outer surface of the angle steel is divided into multiple spans at a predetermined pitch between 1 mm and 5 mm.
4. The torch cutting method for angle steel according to claim 2, characterized in that when the axis of the torch reaches the corner of the outer surface of the corner portion, the axis of the torch passes through the center of curvature of the fillet portion formed on the inner surface of the corner portion.
5. A torch cutting method for channel steel, wherein a channel steel in which a pair of flange portions are connected by a web portion and a pair of corner portions at both ends of the web portion is cut with a torch in a direction perpendicular to the longitudinal direction of the channel steel, When moving the torch starting from the tip of one flange portion of the channel steel, in the order of one flange portion, one corner portion, the web portion, the other corner portion, and the other flange portion, The inclination angle of the torch axis in the direction of torch movement is increased proportionally as the torch moves, from the tip of one flange portion to the corner of the outer surface of one corner portion. The axis of the torch, from the corner of the outer surface of one of the corner portions to the center of the web portion, has its inclination angle in the direction opposite to the direction of torch movement decreased proportionally as the torch moves. The inclination angle of the torch axis in the direction of torch movement is increased proportionally as the torch moves, from the center of the web portion to the corner of the outer surface of the other corner portion. The axis of the torch, from the corner of the outer surface of the other corner portion to the tip of the other flange portion, has an inclination angle of the axis of the torch in the direction opposite to the direction of torch movement that decreases proportionally as the torch moves. A method for torch cutting channel steel, characterized by the following features.
6. The torch movement trajectory on the outer surface of the channel steel is divided into multiple spans at a predetermined pitch, The axis of the torch extends from the tip of one of the flange portions to the corner of the outer surface of one of the corner portions, and the inclination angle of the axis of the torch in the direction of torch movement in each of the divided spans is increased proportionally with each torch movement between the multiple spans. The axis of the torch is such that, from the corner of the outer surface of one of the corner portions to the center of the web portion, the inclination angle of the axis of the torch in the direction opposite to the direction of torch movement in each of the divided spans is proportionally reduced each time the torch moves between the multiple spans. The axis of the torch extends from the center of the web portion to the corner of the outer surface of the other corner portion, and the inclination angle of the torch axis in the direction of torch movement in each of the divided spans is increased proportionally with each torch movement between the multiple spans. The axis of the torch, from the corner of the outer surface of the other corner portion to the tip of the other flange portion, proportionally decreases the inclination angle of the axis of the torch in the direction opposite to the direction of torch movement in each of the divided spans, each time the torch moves between the multiple spans. The torch cutting method for channel steel according to feature 5.
7. The torch cutting method for channel steel according to claim 6, characterized in that the torch movement trajectory on the outer surface of the channel steel is divided into multiple spans at a predetermined pitch between 1 mm and 5 mm.
8. When the axis of the torch reaches the corner of the outer surface of one of the corner portions, the axis of the torch passes through the center of curvature of the fillet formed on the inner surface of one of the corner portions. When the axis of the torch reaches the corner of the outer surface of the other corner portion, the axis of the torch passes through the center of curvature of the fillet formed on the inner surface of the other corner portion. The torch cutting method for channel steel according to feature 6.
9. A method for torch-cutting a square steel pipe, in which a square steel pipe having four web sections connected at the corners is cut with a torch in a direction perpendicular to the longitudinal direction of the square steel pipe, When moving the torch from the center of the cutting direction of any one of the four web sections of the square steel pipe, through the corner section, to the center of the cutting direction of the adjacent web section, The first step is to proportionally increase the inclination angle of the torch axis in the direction of torch movement as the torch moves, from the middle of the web portion to the center of the outer surface of the corner portion. A second step is to proportionally decrease the inclination angle of the torch axis in the direction opposite to the torch movement as the torch moves, from the center of the outer surface of the corner portion to the center of one adjacent web portion, A method for torch cutting of square steel pipes, characterized by having the following features.
10. The torch movement trajectory on the outer surface of the square steel pipe is divided into multiple spans at a predetermined pitch. The first step involves increasing the inclination angle of the torch axis in the direction of torch movement in each of the divided spans proportionally each time the torch moves between the multiple spans, from the middle of the web portion to the center of the outer surface of the corner portion. The second step involves proportionally decreasing the inclination angle of the torch axis in each divided span, in the direction opposite to the torch movement direction, each time the torch moves between the multiple spans, from the center of the outer surface of the corner portion to the center of one adjacent web portion. A torch cutting method for square steel pipes according to 9, characterized by having the following features.
11. The torch cutting method for a square steel pipe according to the 10th, characterized in that the torch movement trajectory on the outer surface of the square steel pipe is divided into multiple spans at a predetermined pitch between 1 mm and 5 mm.
12. The torch cutting method for a square steel pipe according to claim 10, characterized in that when the axis of the torch reaches the center of the outer surface of the corner portion, the axis of the torch passes through the center of curvature of the outer surface of the corner portion.
13. A torch cutting method for angle steel, wherein one flange portion of an angle steel, in which a pair of flange portions are connected at a corner portion, is cut with a torch in a direction perpendicular to the longitudinal direction of the angle steel, and the other flange portion is cut with a torch in a direction inclined with respect to the longitudinal direction of the angle steel, When moving the torch starting from the tip of the flange portion of the other angle steel, in the order of the other flange portion, the corner portion, and the one flange portion, A first step is to proportionally increase the inclination angle of the torch axis in the direction of torch movement as the torch moves, from the tip of the other flange portion to the corner of the outer surface of the corner portion, The torch has a second step of proportionally decreasing the inclination angle of the torch axis in the direction opposite to the torch movement as the torch moves, from the corner of the outer surface of the corner portion to the tip of one flange portion. A method for torch cutting angle steel, characterized in that, at the beginning of the second step, the axis of the torch is tilted until it coincides with a first plane that bisects the inner angle of the corner, and the second step is carried out with the axis of the torch aligned with a second plane that includes the direction of the tilt and is perpendicular to the other flange portion.
14. A torch cutting method for channel steel, wherein a pair of flange portions of channel steel are connected by a web portion and a pair of corner portions at both ends of the web portion, and the pair of flange portions of channel steel are cut with a torch perpendicular to the longitudinal direction of the channel steel, and the web portion is cut with a torch in an inclined direction with respect to the longitudinal direction of the channel steel, When moving the torch starting from the tip of one flange portion of the channel steel, in the order of one flange portion, one corner portion, the web portion, the other corner portion, and the other flange portion, A first step is to proportionally increase the inclination angle of the torch axis in the direction of torch movement as the torch moves, from the tip of one flange portion to the corner of the outer surface of one corner portion, A second step involves proportionally decreasing the inclination angle of the torch axis in the direction opposite to the torch movement as the torch moves, from the corner of the outer surface of one of the corner portions to the center of the web portion. A third step involves proportionally increasing the inclination angle of the torch axis in the direction of torch movement as the torch moves, from the central part of the web portion to the corner of the outer surface of the other corner portion, The fourth step involves proportionally decreasing the inclination angle of the torch axis in the direction opposite to the torch movement as the torch moves, from the corner of the outer surface of the other corner portion to the tip of the other flange portion, In all steps from the first to the fourth, the torch is advanced with its axis aligned with a second plane that includes the inclination direction and is perpendicular to the web portion. A method for torch cutting channel steel, characterized in that, at the beginning of the second and fourth steps, the axis of the torch is tilted until it coincides with a first plane that bisects the inner angle of the corner, before the axis of the torch reaches the corner of the outer surface of the corner portion.
15. A method for cutting a square steel pipe with a torch, wherein a pair of opposing webs of a square steel pipe, in which four webs are connected at the corners, are cut with a torch perpendicular to the longitudinal direction of the square steel pipe, and another pair of opposing webs are cut with a torch in an inclined direction relative to the longitudinal direction of the square steel pipe, When moving the torch from the center of the cutting direction of the other pair of web sections of the square steel pipe, through the corner section to the center of the cutting direction of the adjacent web section, A first step is to proportionally increase the inclination angle of the torch axis in the direction of torch movement as the torch moves, from the middle of the other pair of web portions to the center of the outer surface of the corner portion, The second step involves proportionally decreasing the inclination angle of the torch axis in the direction opposite to the torch movement as the torch moves, from the center of the outer surface of the corner portion to the center of the adjacent web portion. A method for torch cutting a square steel pipe, characterized in that, at the beginning of the second step, the axis of the torch is tilted until it coincides with a first plane that bisects the inner angle of the corner, and the second step is carried out while the axis of the torch is aligned with a second plane that includes the direction of the tilt and is perpendicular to the other pair of web portions.