Spark protection unit and welding method

Abstract

The present invention provides a spark protection unit and welding method that can easily maintain the appearance of protective sheets and prevent the scaffolding from bearing excessive load. [Solution] The spark protection unit 1 comprises a three-dimensional frame-shaped frame 2 positioned to surround the scaffolding 5 for welding work attached to a structure 10 from the outside, and a protective sheet 3 stretched over the frame 2. The frame 2 is provided with arms 25 for attaching the frame 2 to the structure 10, and the frame 2 is installed independently of the scaffolding 5. The spark protection unit 1, which has been pre-assembled on the ground, is lowered from above the scaffolding 5 and positioned to surround the scaffolding 5 from the outside, the arms 25 are attached to the structure 10, and workers perform welding work on the scaffolding 5.

Description

Technical Field

[0001] The present invention relates to a spark curing unit and a welding method using the spark curing unit.

Background Art

[0002] During the construction of a steel-frame structure, welding operations occur at the joint parts between steel columns and at the joint parts between steel beams and steel columns. The welding operations are carried out on scaffolds attached to the structure. However, if people around the site directly look at the welding light (arc light), it is not good for the eyes. Therefore, during welding operations, a curing sheet (flame-proof sheet) is attached to the scaffold to perform spark curing. For example, Patent Document 1 describes surrounding the scaffold with a curing sheet stretched on a frame to perform spark curing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The attachment of the curing sheet is often carried out on-site for each scaffold, and there is a large variation in the installation status depending on individual workers and working environments. Therefore, in some scaffolds, the curing sheet is often loose, etc., and the appearance from the outside is often not good. At the construction site, it is important not only to ensure various types of curing but also to arrange the appearance of various types of curing in order to show the neighborhood that the site is well-managed.

[0005] In Patent Document 1, a protective sheet is stretched and extended to the frame in an aesthetically pleasing manner. However, since the frame is attached to scaffolding, loads applied to the frame, such as wind loads, are transmitted to the scaffolding. Scaffolding for welding work is often designed without considering wind loads, and there is a risk that wind loads applied to the frame will be transmitted to the scaffolding, which could be problematic.

[0006] This invention has been made in view of the above problems, and aims to provide a spark protection unit and welding method that can easily improve the appearance of the protective sheet and prevent the scaffolding from bearing a load. [Means for solving the problem]

[0007] The first invention for achieving the aforementioned objective is a structure The intersection of a steel column and a steel beam, or its vicinity. Attached for welding work one scaffold only A three-dimensional frame-like structure is positioned to surround it from the outside. a frame having a height that does not reach other steel beams adjacent to the steel beam in the height direction. The spark protection unit comprises a protective sheet stretched over the frame, wherein the frame is provided with an attachment portion for attaching the frame to the structure, and the frame is installed independently of the scaffolding.

[0008] The spark protection unit of the present invention has a structure in which a protective sheet is stretched over a three-dimensional frame that surrounds scaffolding attached to a structure from the outside. By using such a spark protection unit, leakage of welding light from the scaffolding to the outside can be prevented, and the appearance of the protective sheet surrounding the scaffolding can be easily maintained. Furthermore, the frame of the spark protection unit has mounting parts for attaching the frame to the structure, eliminating the need to attach the frame to the scaffolding. Therefore, the spark protection unit can be installed independently of the scaffolding, and loads such as wind loads acting on the frame can be prevented from being transmitted to the scaffolding.

[0009] The mounting portion is an arm that protrudes from the frame, and it is desirable that the length of the arm protruding from the frame is adjustable. This allows the arms to be extended to the appropriate length according to the distance to the structure, and the frame to be attached to the structure. Therefore, the spark protection unit can be applied to various welding locations.

[0010] It is desirable that the height of the aforementioned frame be adjustable. This makes it possible to surround scaffolding, which is erected at various heights, with a frame attached to a predetermined location on the structure via an attachment point, and to apply the spark protection unit to various welding locations.

[0011] The second invention is a welding method that uses the spark protection unit of the first invention, characterized in that the pre-assembled spark protection unit is lowered from above a welding scaffold attached to a structure and positioned to surround the scaffold from the outside, the mounting part is attached to the structure, and a worker performs welding work on the scaffold.

[0012] The second invention is a welding method using the spark protection unit of the first invention. By attaching a protective sheet to the frame, the pre-assembled spark protection unit is lowered and installed on the outside of the scaffolding, allowing the scaffolding to be easily enclosed by the spark protection unit, thereby reducing the amount of work required on the scaffolding to install the spark protection unit.

[0013] The frame is made of steel, and it is desirable that workers attach fall protection equipment to the frame before performing welding work. Scaffolding handrails are generally made of aluminum and lack sufficient strength, making them unsuitable for attaching fall protection equipment to workers. On the other hand, by making the frame of the spark protection unit of the present invention out of steel and providing sufficient strength, it becomes possible for workers to attach fall protection equipment to the frame and perform welding work, thereby improving work safety. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a spark curing unit and a welding method that can easily arrange the appearance of the curing sheet and prevent the load burden on the scaffold.

Brief Description of the Drawings

[0015] [Figure 1] Figure showing the spark curing unit 1. [Figure 2] Figure showing the frame 2. [Figure 3] Figure showing the pin 203. [Figure 4] Figure showing the details of the connection part by the upper Y-shaped socket 26. [Figure 5] Figure showing the details of the connection part by the lower Y-shaped socket 26. [Figure 6] Figure showing the details of the connection part by the T-shaped socket 27. [Figure 7] Figure showing the details of the connection part by the L-shaped socket 28. [Figure 8] Figure showing the curing sheet 3. [Figure 9] Figure for explaining the welding method using the spark curing unit 1. [Figure 10] Figure for explaining the welding method using the spark curing unit 1. [Figure 11] Figure showing the frame 2a.

Modes for Carrying Out the Invention

[0016] Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

[0017] (1. Spark curing unit 1) FIG. 1 is a view showing a spark curing unit 1 according to an embodiment of the present invention. The spark curing unit 1 is formed by stretching a curing sheet 3 on a three-dimensional frame-shaped frame 2. The frame 2 of the spark curing unit 1 is arranged so as to surround the welding scaffold 5 attached to the structure 10 from the outside. "Outside" refers to the opposite side of the structure 10 as viewed from the scaffold 5.

[0018] The scaffolding 5 is attached to the structure 10 when welding steel columns 11 together or steel columns 11 to steel beams 12 of the steel-framed structure 10. In this embodiment, welding of steel columns 11 to steel beams 12 is performed. The scaffolding 5 is located at or near the intersection of the steel columns 11 and steel beams 12.

[0019] (2. Frame 2) Figure 2 shows frame 2. Frame 2 has a rear portion 2-1 and left and right side portions 2-2, and its plane is roughly U-shaped. Frame 2 is made of steel and is manufactured using temporary construction materials, which are standard products certified by the Japan Temporary Construction Industry Association. In Figure 2, the x and y directions are two horizontal directions that are orthogonal in the plane, and the z direction is the vertical direction. The x direction corresponds to the extension direction of the steel beam 12, and the y direction corresponds to the direction that is orthogonal in the plane to the extension direction of the steel beam 12. "Left and right" refers to both sides in the x direction.

[0020] The rear portion 2-1 of frame 2 is a rectangular frame-shaped section aligned with the x-direction. In the rear portion 2-1, vertical cylinders 20 (20a), which are cylindrical bodies in the z-direction, are arranged on the left and right, and horizontal cylinders 23, which are cylindrical bodies in the x-direction, are arranged vertically. Y-shaped sockets 26 are arranged at the four corners of the rectangular frame-shaped rear portion 2-1. The Y-shaped sockets 26 are members that connect the ends of cylindrical bodies in three orthogonal directions (x, y, and z directions).

[0021] The upper ends of the left and right vertical cylinders 20a are inserted into the z-direction cylinders of the upper left and right Y-shaped sockets 26, respectively. The outer diameter of the vertical cylinder 20a corresponds to the z-direction cylinder of the Y-shaped socket 26. A vertical inner cylinder 21 is inserted into the lower ends of the left and right vertical cylinders 20, respectively. The vertical inner cylinder 21 is a z-direction cylinder. The outer diameter of the vertical inner cylinder 21 corresponds to the inner diameter of the vertical cylinder 20a.

[0022] A vertical cylinder 22 is inserted into the z-direction cylinder of the lower left and right Y-shaped sockets 26. The vertical cylinder 22 is a cylinder in the z-direction. The outer diameter of the vertical cylinder 22 corresponds to the inner diameter of the z-direction cylinder of the Y-shaped socket 26. The lower end of the vertical inner cylinder 21 is inserted into the vertical cylinder 22. The inner diameter of the vertical cylinder 22 corresponds to the outer diameter of the vertical inner cylinder 21.

[0023] The ends of the upper and lower horizontal cylinders 23 are inserted into the x-direction cylinders of the left and right Y-shaped sockets 26, respectively. The outer diameter of the horizontal cylinders 23 corresponds to the inner diameter of the x-direction cylinders of the Y-shaped sockets 26.

[0024] The side portion 2-2 of frame 2 is a rectangular frame-shaped portion aligned with the y-direction and is positioned to extend from the left and right ends of the rear portion 2-1 toward the structure 10. In the side portion 2-2, another vertical cylinder 20 (20b) is positioned in front of a vertical cylinder 20 (20a), and horizontal cylinders 24 (24a, 24b), which are cylinders in the y-direction, are positioned above and below it. A T-shaped socket 27 is positioned at the front upper corner of the rectangular frame-shaped side portion 2-2, and an L-shaped socket 28 is positioned at the front lower corner. "Front" refers to the side toward the structure 10 in the y-direction. The T-shaped socket 27 is a member that connects the upper end of a cylinder in the z-direction to the center of a cylinder in the y-direction. The L-shaped socket 28 is a member that connects the lower end of a cylinder in the z-direction to the end of a cylinder in the y-direction.

[0025] The upper end of the vertical cylinder 20b is inserted into the z-direction cylinder of the T-shaped socket 27. The inner diameter of this cylinder corresponds to the outer diameter of the vertical cylinder 20b. The vertical inner cylinder 21 is inserted into the lower end of the vertical cylinder 20b.

[0026] A vertical cylinder 22 is inserted into the z-direction cylinder of the L-shaped socket 28. The inner diameter of this cylinder corresponds to the outer diameter of the vertical cylinder 22. The lower end of the vertical inner cylinder 21 is inserted into the vertical cylinder 22.

[0027] The rear ends of the upper and lower horizontal cylinders 24a and 24b are inserted into the y-direction cylinders of the upper and lower Y-shaped sockets 26. The outer diameters of the horizontal cylinders 24a and 24b correspond to the inner diameters of the y-direction cylinders of the Y-shaped sockets 26. "Rear" refers to the opposite side of the structure 10 in the y-direction.

[0028] The front end of the upper horizontal cylinder 24a is inserted into the y-direction cylinder of the T-type socket 27, passing through the cylinder and protruding forward from it. The inner diameter of the T-direction cylinder corresponds to the outer diameter of the horizontal cylinder 24a. The rear end of the arm 25 is inserted into the front end of the horizontal cylinder 24a. The arm 25 is a horizontal cylinder extending in the y-direction. The outer diameter of the arm 25 corresponds to the inner diameter of the horizontal cylinder 24a.

[0029] The front end of the lower horizontal cylinder 24b is inserted into the y-direction cylinder of the L-shaped socket 28. The inner diameter of this cylinder corresponds to the outer diameter of the horizontal cylinder 24b.

[0030] In the rear portion 2-1 of frame 2, a pair of braces 29 are provided in an X shape between the left and right vertical cylindrical bodies 20a. Also, in the left and right side portions 2-2 of frame 2, a pair of braces 29 are provided in an X shape between the front and rear vertical cylindrical bodies 20a and 20b.

[0031] As shown in Figure 3, the vertical cylinders 20a and 20b are provided with pins 203 for attaching the brace 29. Rings 291 are provided at both ends of the brace 29, and the pins 203 of the vertical cylinders 20a and 20b are passed through these rings 291.

[0032] The ring 291 is secured by a claw 204 provided on the pin 203, preventing it from falling off the pin 203. The claw 204 is biased outward by a spring (not shown), so that when the pin 203 is passed through the ring 291, the claw 204 retracts into the inside of the pin 203. Once the ring 291 has passed the position of the claw 204, the claw 204 moves forward outward to secure the ring 291.

[0033] (3. Connection points by each socket) Figure 4(a) shows the details of the connection made by the upper Y-shaped socket 26. The upper end of the vertical cylinder 20a is fixed to the z-direction cylinder of the Y-shaped socket 26 using bolts 71 (71a).

[0034] Figure 4(b) shows the cross-sections of the vertical cylinder 20a and the z-direction cylinder of the Y-shaped socket 26 at the position of the bolt 71a (referring to the cross-section perpendicular to the axial direction of the cylinder; the same applies hereinafter). A through hole 201 is provided at the upper end of the vertical cylinder 20a, penetrating the outer circumferential surface of the vertical cylinder 20a. A through hole 261 is also provided in the z-direction cylinder of the Y-shaped socket 26, penetrating the outer circumferential surface of the cylinder. The through holes 201 and 261 are provided at positions 180° apart around the axis of the cylinder.

[0035] The upper end of the vertical cylinder 20a is inserted into the z-direction cylinder of the Y-shaped socket 26 so that the through hole 201 aligns with the through hole 261. The shaft of the bolt 71a is inserted into the z-direction cylinder of the Y-shaped socket 26 and the through holes 261 and 201 of the vertical cylinder 20a from one through hole 261 side, and a nut 72 is tightened onto the shaft that protrudes from the other through hole 261. This fixes the upper end of the vertical cylinder 20a to the Y-shaped socket 26.

[0036] The left and right ends of the upper horizontal cylinder 23 are fixed to the x-direction cylinder of the Y-shaped socket 26 using bolts 71 (71b).

[0037] Figure 4(c) shows a cross-section of the horizontal cylinder 23 and the x-direction cylinder of the Y-shaped socket 26 at the position of the bolt 71b. The horizontal cylinder 23 is provided with a through hole 231 that penetrates the outer circumferential surface of the horizontal cylinder 23. The x-direction cylinder of the Y-shaped socket 26 is also provided with a through hole 261 that penetrates the outer circumferential surface of the cylinder. The through holes 231 and 261 are provided at positions 180° apart around the axis of the cylinders.

[0038] The horizontal cylinder 23 is inserted into the x-direction cylinder of the Y-shaped socket 26 such that the through hole 231 aligns with the through hole 261. The shaft of the bolt 71b is inserted into the x-direction cylinder of the Y-shaped socket 26 and the through holes 261 and 231 of the horizontal cylinder 23 from one through hole 261 side, and a nut 72 is tightened onto the shaft that protrudes from the other through hole 261. This fixes the end of the horizontal cylinder 23 to the Y-shaped socket 26.

[0039] The rear end of the upper horizontal cylinder 24a is fixed to the y-direction cylinder of the Y-shaped socket 26 using bolts 71 (71c).

[0040] The cross-sections of the horizontal cylinder 24a and the Y-shaped socket 26 in the y-direction at the position of bolt 71c are the same as the cross-sections of the horizontal cylinder 23 and the Y-shaped socket 26 in the x-direction at the position of bolt 71b. That is, as shown in Figure 4(c), the horizontal cylinder 24a is provided with a through hole 241 that penetrates the outer circumferential surface of the horizontal cylinder 24a. The Y-shaped socket 26 is also provided with a through hole 261 that penetrates the outer circumferential surface of the cylinder. The through holes 241 and 261 are provided at positions 180° apart around the axis of the cylinder.

[0041] The rear end of the horizontal cylinder 24a is inserted into the y-direction cylinder of the Y-shaped socket 26 such that the through hole 241 aligns with the through hole 261. The shaft of the bolt 71c is inserted into the y-direction cylinder of the Y-shaped socket 26 and the through holes 261 and 241 of the horizontal cylinder 24a from one through hole 261 side, and a nut 72 is tightened onto the shaft protruding from the other through hole 261. This fixes the rear end of the horizontal cylinder 24a to the Y-shaped socket 26.

[0042] Figure 5(a) shows the details of the connection part by the lower Y-shaped socket 26. The vertical inner cylinder 21 is fixed to the lower end of the vertical cylinder 20a using a retaining pin 81 (81a).

[0043] Figure 5(b) shows a cross-section of the vertical cylinder 20a and the vertical inner cylinder 21 at the position of the retaining pin 81a. A through hole 202 is provided at the lower end of the vertical cylinder 20a, penetrating the outer surface of the vertical cylinder 20a. A through hole 211 is provided in the vertical inner cylinder 21, penetrating the outer surface of the vertical inner cylinder 21. As shown in Figure 5(a), multiple through holes 211 are provided at intervals in the z direction. Each of the through holes 202 and 211 is provided at a position 180° apart around the axis of the cylinder.

[0044] The vertical inner cylinder 21 is inserted into the lower end of the vertical cylinder 20a such that one of the multiple through holes 211 in the z direction aligns with the through hole 202. The vertical inner cylinder 21 is fixed to the lower end of the vertical cylinder 20a by inserting a retaining pin 81a from one through hole 202 side into the through holes 202 and 211 of the vertical cylinder 20a and the vertical inner cylinder 21, and passing a cotter pin 82 through the end of the retaining pin 81a protruding from the other through hole 202.

[0045] The lower end of the vertical inner cylinder 21 is fixed to the z-direction cylinder of the lower Y-shaped socket 26 using the vertical cylinder 22 and bolt 71 (71d).

[0046] Figure 5(c) shows cross-sections of the vertical inner cylinder 21, the vertical cylinder 22, and the z-direction cylinder of the Y-shaped socket 26 at the position of the bolt 71d. A through hole 212 is provided at the lower end of the vertical inner cylinder 21, penetrating the outer circumferential surface of the vertical inner cylinder 21. A through hole 221 is provided in the vertical cylinder 22, penetrating the outer circumferential surface of the vertical cylinder 22. A through hole 261 is provided in the z-direction cylinder of the Y-shaped socket 26, penetrating the outer circumferential surface of the cylinder. Each of the through holes 212, 221, and 261 is provided at positions 180° apart around the axis of the cylinder.

[0047] The vertical cylinder 22 is inserted into the z-direction cylinder of the Y-shaped socket 26 so that the through hole 221 aligns with the through hole 261. The lower end of the vertical inner cylinder 21 is inserted into the vertical cylinder 22 so that the through hole 212 aligns with the through holes 221 and 261. The shaft of the bolt 71d is inserted from one through hole 261 into the z-direction cylinder of the Y-shaped socket 26, the vertical cylinder 22, and the through holes 261, 221, and 212 of the vertical inner cylinder 21, and a nut 72 is tightened onto the shaft protruding from the other through hole 261. This fixes the lower end of the vertical inner cylinder 21 to the Y-shaped socket 26.

[0048] The left and right ends of the lower horizontal cylinder 23 are fixed to the x-direction cylinder of the Y-type socket 26 using bolts 71 (71e), in the same manner as the upper horizontal cylinder 23. The rear end of the lower horizontal cylinder 24b is also fixed to the y-direction cylinder of the Y-type socket 26 using bolts 71 (71f), in the same manner as the upper horizontal cylinder 24a. Figure 5(d) shows the cross-sections of the x-direction cylinders of the horizontal cylinder 23 and the Y-type socket 26 at the position of bolt 71e, and the cross-sections of the y-direction cylinders of the horizontal cylinder 24b and the Y-type socket 26 at the position of bolt 71f.

[0049] Figure 6(a) shows the details of the connection using the T-shaped socket 27. The upper end of the vertical cylinder 20b is fixed to the cylinder in the z direction of the T-shaped socket 27 using a bolt 71 (71g).

[0050] Figure 6(b) shows a cross-section of the vertical cylinder 20b and the z-direction cylinder of the T-shaped socket 27 at the position of the bolt 71g. A through hole 201 is provided at the upper end of the vertical cylinder 20b, penetrating the outer surface of the vertical cylinder 20b. A through hole 271 is also provided in the z-direction cylinder of the T-shaped socket 27, penetrating the outer surface of the cylinder. The through holes 201 and 271 are located at positions 180° apart around the axis of the cylinders.

[0051] The upper end of the vertical cylinder 20b is inserted into the z-direction cylinder of the T-type socket 27 so that the through hole 201 aligns with the through hole 271. The shaft of the bolt 71g is inserted into the z-direction cylinder of the T-type socket 27 and the through holes 271 and 201 of the vertical cylinder 20b from one through hole 271 side, and a nut 72 is tightened onto the shaft protruding from the other through hole 271. This fixes the upper end of the vertical cylinder 20b to the T-type socket 27.

[0052] The front end of the upper horizontal cylinder 24a is fixed to the y-direction cylinder of the T-shaped socket 27 using bolts 9.

[0053] Figure 6(c) shows a cross-section of the horizontal cylinder 24a and the T-shaped socket 27 in the y-direction at the position of the bolt 9. A bolt hole 272 with threads on its inner surface is provided on the outer circumferential surface of the cylinder. The shaft of the bolt 9 is screwed into the bolt hole 272 using an impact wrench or the like, and the tip of the bolt presses the horizontal cylinder 24a, which is inserted into the cylinder, against the inner surface of the cylinder. This fixes the front end of the horizontal cylinder 24a to the T-shaped socket 27.

[0054] The arm portion 25 is fixed to the front end of the horizontal cylindrical body 24a using a retaining pin 81 (81b).

[0055] Figure 6(d) shows a cross-section of the arm portion 25 and the horizontal cylinder 24a at the position of the retaining pin 81b. The arm portion 25 is provided with a through hole 251 that penetrates the outer circumferential surface of the arm portion 25. The front end of the horizontal cylinder 24a is also provided with a through hole 242 that penetrates the outer circumferential surface of the horizontal cylinder 24a. Each of the through holes 251 and 242 is provided at positions 180° apart around the axis of the cylinder. As shown in Figure 6(a), multiple through holes 251 are provided at intervals in the y direction.

[0056] The arm portion 25 is inserted into the horizontal cylindrical body 24a such that one of the multiple through holes 251 in the y direction overlaps with the through hole 242. The arm portion 25 is fixed to the horizontal cylindrical body 24a by inserting a retaining pin 81b into the through holes 242 and 251 from one side of the through hole 242, and passing a cotter pin 82 through the end of the retaining pin 81b protruding from the other through hole 242.

[0057] Figure 7(a) shows the details of the connection part using the L-shaped socket 28. Similar to the vertical cylinder 20a described above, the vertical inner cylinder 21 is fixed to the lower end of the vertical cylinder 20b using a retaining pin 81 (81c). Figure 7(b) shows a cross-section of the vertical cylinder 20b and the vertical inner cylinder 21 at the position of the retaining pin 81c.

[0058] The lower end of the vertical inner cylinder 21 is fixed to the z-direction cylinder of the L-shaped socket 28 using the vertical cylinder 22 and bolt 71 (71h), as described above.

[0059] Figure 7(c) shows cross-sections of the vertical inner cylinder 21, the vertical cylinder 22, and the z-direction cylinder of the L-shaped socket 28 at the position of the bolt 71h. The z-direction cylinder of the L-shaped socket 28 is provided with through holes 281 that penetrate the outer surface of the cylinder. The through holes 281 are provided at positions 180° apart around the axis of the cylinder. The shaft of the bolt 71h is inserted into the z-direction cylinder of the L-shaped socket 28, the vertical cylinder 22, and the through holes 281, 221, and 212 of the vertical inner cylinder 21 from one of the through holes 281, and a nut 72 is tightened onto the shaft that protrudes from the other through hole 281. This fixes the lower end of the vertical inner cylinder 21 to the L-shaped socket 28.

[0060] The front end of the lower horizontal cylinder 24b is fixed to the y-direction cylinder of the L-shaped socket 28 using bolts 71 (71i).

[0061] Figure 7(d) shows a cross-section of the horizontal cylinder 24b and the y-direction cylinder of the L-shaped socket 28 at the position of the bolt 71i. A through hole 242 is provided at the front end of the horizontal cylinder 24b, penetrating the outer circumferential surface of the horizontal cylinder 24b. A through hole 281 is also provided in the y-direction cylinder of the L-shaped socket 28, penetrating the outer circumferential surface of the cylinder. The through holes 242 and 281 are provided at positions 180° apart around the axis of the cylinders.

[0062] The front end of the horizontal cylinder 24b is inserted into the y-direction cylinder of the L-shaped socket 28 such that the through hole 242 aligns with the through hole 281. The shaft of the bolt 71i is inserted into the y-direction cylinder of the L-shaped socket 28 and the through holes 281 and 242 of the horizontal cylinder 24b from one through hole 281 side, and a nut 72 is tightened onto the shaft protruding from the other through hole 281. This fixes the front end of the horizontal cylinder 24a to the L-shaped socket 28.

[0063] The height of frame 2 can be adjusted by which through-hole 211 the retaining pin 81 is inserted into when fixing the vertical inner cylinder 21 to the lower end of the vertical cylinder 20 (20a, 20b). Also, the length of the arm 25 protruding from frame 2 can be adjusted by which through-hole 251 the retaining pin 81 is inserted into when fixing the arm 25 to the front end of the horizontal cylinder 24a.

[0064] (4. Protective sheet 3) Figure 8 shows the protective sheet 3. As shown in Figure 8, the protective sheet 3 is a T-shaped surface material made up of four rectangular sections. Each rectangular section is a back section 31 that covers the back section 2-1 of the frame 2, side sections 32 that cover the left and right side sections 2-2 of the frame 2, and a bottom section 33 that covers the bottom surface of the frame 2. Grommets 35 are provided at predetermined intervals around the outer circumference of the protective sheet 3, and as shown in Figure 1, each of the above sections of the protective sheet 3 is attached to the frame 2 by wires 4 (for example, string or cable ties) passed through the grommets 35. A core rod 34 for maintaining the shape is provided in the bottom section 33 of the protective sheet 3. The extension direction of the core rod 34 corresponds to the x-direction mentioned above. As the protective sheet 3, a surface material having flame retardancy, fire resistance, or non-combustibility, such as a flame-retardant sheet, or a combination of a mesh sheet and a flame-retardant sheet, or a combination of a vertical net and a flame-retardant sheet can be used.

[0065] (5. Welding method using spark protection unit 1) Next, the procedure (welding method) for welding work using the spark protection unit 1 will be described. In this embodiment, first, as shown in Figure 9(a), a scaffolding 5 for welding work is installed at the intersection of the steel column 11 and the steel beam 12, at a height approximately equal to the lower end of the steel beam 12. The scaffolding 5 is attached to the steel column 11 and steel beam 12 of the structure 10. A handrail 13 made of single pipes or the like is provided on top of the steel beam 12.

[0066] Furthermore, the spark protection unit 1 is assembled in advance on the ground or elsewhere. At this time, as shown in Figure 9(b), the back portion 31 and left and right side portions 32 of the protective sheet 3 are stretched over the back portion 2-1 and left and right side portions 2-2 of the frame 2, and the above portions of the protective sheet 3 are attached to the frame 2 with wires 4 passed through the grommet holes 35. The height of the frame 2 and the protruding length of the arm portions 25 are adjusted during the assembly of the spark protection unit 1. The bottom portion 33 of the protective sheet 3 is not attached to the frame 2 at this point.

[0067] Next, the frame 2 of the spark protection unit 1 is lifted by a crane (not shown), and the spark protection unit 1 is lowered from above the scaffolding 5 as shown by arrow a in Figure 10(a), and the spark protection unit 1 is installed so as to surround the scaffolding 5 from the outside. At this time, the bottom portion 33 of the protective sheet 3 is hanging downwards, which prevents interference between the bottom portion 33 of the protective sheet 3 and the scaffolding 5 when lowering the spark protection unit 1.

[0068] After installing the spark protection unit 1 to surround the scaffolding 5 from the outside, the ends of the arms 25 of the frame 2 are fixed to the handrail 13 with fasteners 14 such as right-angle clamps, as shown in Figure 10(b). In addition, horizontal members 18 such as single pipes are fixed to the lower flange of the steel beam 12 with fasteners 19 such as catch clamps, and the vertical cylindrical body 20 (20b) of the frame 2 is fixed to the horizontal members 18 with fasteners 17 such as right-angle clamps.

[0069] As a result, frame 2 is supported from the steel beam 12 of structure 10 via handrails 13 and horizontal members 18, etc. Frame 2 is installed independently of scaffolding 5 without being attached to it. "Independently" means that frame 2 is not attached to scaffolding 5. The scaffolding 5 is positioned near the lower end of the steel beam 12 in the height direction and near the outside of the steel column 11 in the plane. Therefore, the height adjustment of frame 2 is done to match the beam depth of the steel beam 12 so that it can cover the scaffolding 5, and the length adjustment of arm portions 25 is done to match the cross-sectional dimensions of the steel column 11 so that the arm portions 25 can be attached to handrails 13.

[0070] After attaching frame 2 to steel beam 12, as shown in Figure 1, the bottom portion 33 of the protective sheet 3 is stretched over the bottom surface of frame 2 below the scaffolding 5, and the bottom portion 33 is attached to frame 2 by wire 4 passed through grommet holes 35 in the bottom portion 33.

[0071] After installing the spark protection unit 1 on the outside of the scaffolding 5, the worker performs welding work on the steel columns 11 and steel beams 12 on the scaffolding 5. The worker can attach their fall protection equipment to the frame 2 and perform the welding work.

[0072] As described above, the spark protection unit 1 of this embodiment has a structure in which a protective sheet 3 is stretched over a three-dimensional frame 2 that surrounds the scaffolding 5 attached to the structure 10 from the outside. By using such a spark protection unit 1, it is possible to prevent welding light from leaking out from the scaffolding 5 to the outside. Furthermore, if the protective sheet 3 is attached on-site for each scaffolding 5 as in the conventional method, variations in the installation condition due to the worker and the work environment, such as sagging of the protective sheet 3, can occur. However, by using the spark protection unit 1 of this embodiment, the appearance of the protective sheet 3 surrounding the scaffolding 5 can be easily maintained.

[0073] Furthermore, the frame 2 of the spark protection unit 1 has arm sections 25 and the like as attachment points for attaching the frame 2 to the structure 10, so there is no need to attach the spark protection unit 1 to the scaffolding 5. Therefore, the spark protection unit 1 does not have attachment points for attaching the spark protection unit 1 to the scaffolding 5, and the spark protection unit 1 can be installed independently of the scaffolding 5, preventing loads such as wind loads acting on the frame 2 from being transmitted to the scaffolding 5.

[0074] Furthermore, in this embodiment, the arm portion 25, whose protruding length from the frame 2 is adjustable, is used as an attachment point for attaching the frame 2 to the structure 10. Therefore, the arm portion 25 can be extended to an appropriate length according to the distance to the handrail 13 provided on the structure 10, and the frame 2 can be attached to the structure 10. Also, since the height of the frame 2 is adjustable, it becomes possible to surround scaffolding 5, which is installed at various heights, with the frame 2. As a result, the spark protection unit 1 can be applied to various welding locations. Specifically, for example, one frame 2 can be repurposed for beams with different beam depths or columns with different cross-sectional dimensions.

[0075] Furthermore, in this embodiment, by attaching a protective sheet 3 to the frame 2 and then lowering the pre-assembled spark protection unit 1 to the outside of the scaffolding 5, the scaffolding 5 can be easily enclosed by the spark protection unit 1, reducing the amount of work required on the scaffolding 5 to install the spark protection unit 1. In addition, the handrails of the scaffolding 5 are generally made of aluminum and do not have sufficient strength, making them unsuitable as a target for attaching fall protection equipment for workers. However, by making the frame 2 of the spark protection unit 1 in this embodiment out of steel and having sufficient strength, it becomes possible for workers to attach fall protection equipment to the frame 2 and perform welding work, thereby improving work safety.

[0076] However, the present invention is not limited to the above embodiments. For example, in this embodiment, the arm portion 25 of the frame 2 is attached to the handrail 13 of the structure 10, but the attachment location of the arm portion 25 is not particularly limited and can be attached to various predetermined locations on the structure 10 depending on the height of the scaffolding 5. Also, the structure 10 to which the spark protection unit 1 is attached is not particularly limited and can be any structure where welding work is performed.

[0077] Furthermore, in the spark protection unit 1, the height of the back portion 31 and side portion 32 of the protective sheet 3 can be made variable to match the height of the frame 2. However, since the protective sheet 3 is easily punctured by sparks, etc., it has low reusability, and considering that the protective sheet 3 is stretched over the frame 2 on the ground beforehand, it is more practical to prepare multiple protective sheets 3 with different heights for the back portion 31 and side portion 32 and use the protective sheet 3 that matches the height of the frame 2.

[0078] Furthermore, the shape and configuration of the frame 2 are not particularly limited. For example, a scaffolding 5 having an L-shaped plane may be provided at the corner of the structure 10, and for such scaffolding 5, it is preferable to attach a protective sheet 3 to a frame 2a formed by combining the aforementioned back portions 2-1 in an L-shape, as shown in Figure 11, and use it as a spark protection unit.

[0079] The upper horizontal cylinder 23 of the adjacent back portion 2-1 is inserted into the x-direction and y-direction cylinders of the upper Y-shaped socket 26 (26a), respectively, and fixed to each cylinder using bolts 71, similar to the example in Figure 4(c). The upper end of the vertical cylinder 20a is fixed to the z-direction cylinder of the Y-shaped socket 26a using bolts 71, similar to the example in Figure 4(b). The lower end of the vertical inner cylinder 21 is fixed to the vertical cylinder 20a using retaining pins 81, similar to the example in Figure 5(b).

[0080] The lower horizontal cylinder 23 of the adjacent back portion 2-1 is inserted into the x-direction and y-direction cylinders of the lower Y-shaped socket 26 (26a), respectively, and is fixed to each cylinder using bolts 71, similar to the example in Figure 5(d). The lower end of the vertical inner cylinder 21 is fixed to the z-direction cylinder of the lower Y-shaped socket 26a using the vertical cylinder 22 and bolts 71, similar to the example in Figure 5(c).

[0081] Furthermore, a retaining member 15 is provided between the upper horizontal cylinders 23 of both rear sections 2-1 to maintain a 90° intersection angle between the two rear sections 2-1 of the frame 2a. Both ends of the retaining member 15 are fixed to each rear section 2-1, the upper horizontal cylinder 23 of 2-1 by fixing devices 16 such as adjustable clamps. A retaining member 15 is similarly provided for the lower horizontal cylinders 23 of both rear sections 2-1. These retaining members 15 are attached to the frame 2a after the spark protection unit, consisting of the frame 2a and the protective sheet 3, has been lowered by a crane or the like and positioned outside the scaffolding 5. This prevents interference between the retaining member 15 and the scaffolding 5 when the spark protection unit is lowered by a crane or the like.

[0082] Furthermore, the adjustment mechanisms for the height of the frame 2 and the protruding length of the arm portion 25 are not limited to those described above. For example, a vertical inner cylinder 21 may be screwed onto the lower end of the vertical cylinder 20 (20a, 20b), allowing the height of the frame 2 to be adjusted by rotation of the vertical inner cylinder 21 around its axis. The same applies to the protruding length of the arm portion 25; the arm portion 25 may be screwed onto the front end of the horizontal cylinder 24a, allowing the arm portion 25 to move forward and backward by rotation of the arm portion 25 around its axis.

[0083] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the technical idea disclosed herein, and these will naturally also fall within the technical scope of the present invention. [Explanation of symbols]

[0084] 1: Spark protection unit 2, 2a: Frame 3: Protective sheet 5: Scaffolding 10: Structure 20, 20a, 20b: Vertical cylinder 21: Vertical inner cylinder 22: Vertical cylinder 23, 24, 24a, 24b: Horizontal cylinder 25: Arm 26, 26a: Y-type socket 27: T-type socket 28: L-shaped socket 29: Brace

Claims

1. A three-dimensional frame-like structure that is positioned to surround only one scaffolding for welding work attached to or near the intersection of steel columns and steel beams in a structure, the frame having a height that does not reach other steel beams adjacent to the steel beam in the height direction, A protective sheet stretched over the aforementioned frame, It is equipped with, The frame is provided with an attachment portion for attaching the frame to the structure. The spark protection unit is characterized in that the frame is installed independently of the scaffolding.

2. The aforementioned mounting portion is an arm portion that protrudes from the frame, The spark protection unit according to claim 1, characterized in that the protrusion length of the arm from the frame is adjustable.

3. The spark protection unit according to claim 1, characterized in that the height of the frame is adjustable.

4. A welding method using the spark protection unit described in claim 1, The pre-assembled spark protection unit is lowered from above a welding scaffold attached to the structure and positioned to surround the scaffold from the outside, and the mounting part is attached to the structure. A welding method characterized in that a worker performs welding work on the aforementioned scaffolding.

5. The welding method according to claim 4, characterized in that the frame is made of steel, and the worker attaches fall protection equipment to the frame and performs the welding work.

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