Protective cap and method for manufacturing protective cap

Abstract

To provide a protective cap which protects a female joint or a male joint and enables easy attachment / detachment, and to provide a production method of a steel pipe.SOLUTION: A protective cap is attached to a mechanical joint member which is joined to an end of a steel pipe, formed by a cylindrical body which connects the steel pipe in an axial direction, and includes a male joint and a female joint. The protective cap includes: a peripheral surface protective part which contacts with an outer peripheral surface or an inner peripheral surface of the cylindrical body; and a tip protective part which continues into the peripheral surface protective part and contacts with a tip of the cylindrical body.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a curing cap to be attached to a female joint or a male joint of a mechanical joint axially joined to the end of a steel pipe, and a method for manufacturing the curing cap.

Background Art

[0002] For example, Patent Document 1 discloses a steel pipe column structure in which a plurality of steel pipes are arranged axially and their small ends are abutted and connected to each other. Although it is known to weld when connecting the small ends of steel pipes, for example, at a site where sparks cannot be generated such as a renovation work site, one steel pipe is fitted into the other steel pipe, or a male thread provided on the outer periphery of one steel pipe is screwed into a female thread provided on the inner periphery of the other steel pipe to connect the two steel pipes.

[0003] When fitting or screwing two steel pipes to connect them, if the fitting surfaces that fit each other, or the peripheral surfaces of the joint portions where male and female threads are provided, are damaged, deformed, or foreign matter adheres between them, they cannot be surely fitted or screwed. Therefore, when transporting the steel pipes, etc., a wrap or sheet is wound around the fitting surface and the peripheral surface for curing so that the peripheral surfaces of the fitting surface, male thread, and female thread provided on the joint portion are not damaged.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As mentioned above, when wrapping wrap or sheets around the mating surfaces or circumferential surfaces of joints, it is easy to wrap the wrap around the outer surface of the male joint, but when wrapping wrap or sheets around the inner surface of the female joint, it is not only difficult to apply tension, but there is also a risk that it will easily peel off. Furthermore, even if the wrap is wrapped once, it may need to be peeled off and re-wrapped for marking or verification, which presents a challenge in terms of cumbersome work.

[0006] The present invention has been made in view of the above problems, and its main objective is to provide a protective cap for protecting mechanical joints that can be easily attached and detached, and a method for manufacturing the protective cap. [Means for solving the problem]

[0007] To achieve this objective, the protective cap of the present invention is joined to the end of a steel pipe and connects the steel pipe in the axial direction. Furthermore, it has outer and inner surfaces that are parallel to the outer and inner surfaces of the steel pipe. Consists of a cylindrical body Male connector and Mechanical joint member with female connector Female connector A protective cap to be attached to the cylindrical body comprises a circumferential protective portion that contacts the inner circumferential surface of the cylindrical body, and a tip protective portion that is continuous with the circumferential protective portion and contacts the tip of the cylindrical body, The device comprises a circumferential facing portion that is continuous with the tip curing portion and faces the circumferential curing portion across the cylindrical body, wherein the circumferential curing portion is made by applying a sheet-like cushioning material made of polyethylene resin along the curved surface of the cylindrical body over the entire circumference of the inner circumferential surface, and the ends of the sheet-like cushioning material in the circumferential direction are compressed and abutted together in the circumferential direction. It is characterized by the following: Furthermore, in a protective cap to be attached to a male joint of a mechanical joint member, the cap comprises a circumferential protective portion that abuts against the outer surface of the cylindrical body, a tip protective portion that is continuous with the circumferential protective portion and abuts against the tip of the cylindrical body, and a circumferential facing portion that is continuous with the tip protective portion and faces the circumferential protective portion across the cylindrical body, wherein the circumferential facing portion is formed by applying a sheet-like cushioning material along the curved surface of the cylindrical body over the entire circumference of the inner surface, and the ends of the sheet-like cushioning material in the circumferential direction are compressed and abutted together in the circumferential direction.

[0008] Furthermore, the protective cap of the present invention is A protective cap for a mechanical joint member, which is attached to the end of a steel pipe and connects the steel pipe in the axial direction, and which has a male joint and a female joint made of a cylindrical body having an outer and inner circumferential surface parallel to the outer and inner circumferential surfaces of the steel pipe, comprises a circumferential protective portion that abuts against the outer or inner circumferential surface of the cylindrical body, a tip protective portion that is continuous with the circumferential protective portion and abuts against the tip of the cylindrical body, and a circumferential facing portion that is continuous with the tip protective portion and faces the circumferential protective portion across the cylindrical body, wherein a reinforcing layer is provided on the outer surfaces of the circumferential protective portion, the tip protective portion and the circumferential facing portion, and the outer surfaces include the surface facing the cylindrical body and the surface exposed to the outside when attached to the cylindrical body. It is characterized by the following:

[0009] Furthermore, the protective cap of the present invention is characterized in that an ultraviolet-preventive layer is laminated on the surface of the reinforcing layer.

[0011] Furthermore, the protective cap of the present invention is characterized in that the circumferential protective portion abuts against at least the threaded portion provided on the cylindrical body.

[0012] Furthermore, the curing cap of the present invention has the circumferential curing portion The base endIt is characterized by having an extended step surface protection portion that faces a step surface that protrudes from the outer or inner circumferential surface of the cylindrical body.

[0013] The protective cap of the present invention comprises a circumferential protective portion that contacts the outer or inner circumferential surface of a mechanical joint member made of a cylindrical body, and a tip protective portion that is continuous with the circumferential protective portion and contacts the tip of the cylindrical body. This makes it possible to prevent damage to the outer circumferential surface and tip of the male joint or the inner circumferential surface and tip of the female joint that constitute the mechanical joint member.

[0014] Furthermore, the circumferential curing section and the tip curing section abut against the outer surface and tip of the male fitting or the inner surface and tip of the female fitting, and are shaped to conform to the shape of the male fitting or female fitting. Therefore, it is possible to easily attach to and detach from the male fitting or female fitting of a steel pipe.

[0015] Furthermore, because the circumferential and tip protection sections are in contact with the outer surface and tip of the male fitting or the inner surface and tip of the female fitting, foreign matter is less likely to adhere to the outer surface and tip of the male fitting or the inner surface and tip of the female fitting. Therefore, when removing the protection cap and fitting the male fitting of one steel pipe into the female fitting of the other steel pipe, fitting is not hindered by the adhesion of foreign matter, making fitting easy. In addition, since the circumferential and tip protection sections are continuous, it is possible to prevent foreign matter from entering the outer surface and tip of the male fitting or the inner surface and tip of the female fitting from between the circumferential and tip protection sections.

[0016] Furthermore, since a reinforcing layer is provided on the outer surface, external impacts are protected by the reinforcing layer, making it possible to more reliably protect the outer surface and tip of the male connector or the inner surface and tip of the female connector. In addition, even when the protective cap is removed from the male or female connector for storage, the reinforcing layer can suppress deformation and damage caused by external impacts. Moreover, since an ultraviolet-preventive layer is laminated on the surface of the reinforcing layer, it is possible to suppress deterioration of the reinforcing layer due to ultraviolet rays.

[0017] Furthermore, by bringing the circumferential protection portion into contact with at least the threaded portion provided on the cylindrical body, it is possible to prevent damage to the male threads of the male fitting and the female threads of the female fitting, and to suppress the adhesion of foreign matter to the male threads of the male fitting and the female threads of the female fitting. As a result, the protective cap can be removed, and the male thread of one steel pipe can be easily screwed into the female thread of the other steel pipe and tightened securely.

[0018] Furthermore, since it has a circumferential facing portion that is continuous with the tip curing portion and faces the circumferential curing portion across the cylindrical body, the tip curing portion forms the bottom, and the circumferential curing portion and the circumferential facing portion form an annular groove facing each other. As a result, it is possible to cover the end of a male or female fitting so as to accommodate it along the circumferential direction. Therefore, it is possible to provide a curing cap that is easy to attach to and detach from a male or female fitting.

[0019] Furthermore, since the stepped surface protection section protrudes from the outer or inner circumferential surface of the cylindrical body and faces the stepped surface where the tips of the female or male connectors meet, it is possible to suppress damage to this stepped surface and the adhesion of foreign matter, etc. Therefore, when fitting the male connector into the female connector, it is possible to bring the male and female connectors closer together axially and connect them securely. In addition, since the stepped surface protection section is provided continuously with the circumferential surface protection section, it is possible to prevent foreign matter, etc. from entering between the stepped surface protection section and the circumferential surface protection section.

[0020] Furthermore, the method for manufacturing the protective cap of the present invention is characterized by covering the outer or inner circumferential surface of the cylindrical body and the tip of the cylindrical body with a cushioning material, thereby forming the circumferential protective portion and the tip protective portion to be continuous. In addition, the method is characterized by applying a curable resin to the outer surfaces of the circumferential protective portion and the tip protective portion to form a reinforcing layer.

[0021] According to the method for manufacturing the curing cap of the present invention, by covering the outer peripheral surface and tip of the male joint or the inner peripheral surface and tip of the female joint with a cushioning material, it becomes possible to arrange the cushioning material according to the shapes of the male joint and the female joint. Further, it becomes possible to easily form a reinforcing layer on the outer surface of the circumferential surface curing portion and the tip curing portion.

Effects of the Invention

[0022] According to the present invention, it becomes possible to provide a curing cap that cures the mechanical joint portion and is easily detachable, and a method for manufacturing the curing cap.

Brief Description of the Drawings

[0023] [Figure 1] It is a diagram showing a steel pipe column to which the curing cap is to be attached in an embodiment of the present invention. [Figure 2] It is a diagram showing a female joint of a steel pipe column in an embodiment of the present invention. [Figure 3] It is a diagram showing a male joint of a steel pipe column in an embodiment of the present invention. [Figure 4] It is a cross-sectional view showing the state of the curing cap attached to the female joint in an embodiment of the present invention. [Figure 5] It is a perspective view showing the curing cap for the female joint in an embodiment of the present invention. [Figure 6] It is a cross-sectional view showing the state of the curing cap attached to the male joint in an embodiment of the present invention. [Figure 7] It is a perspective view showing the curing cap for the male joint in an embodiment of the present invention. [Figure 8] It is a diagram showing a method for manufacturing the curing cap for the female joint in an embodiment of the present invention (Part 1). [Figure 9] It is a diagram showing a method for manufacturing the curing cap for the female joint in an embodiment of the present invention (Part 2). [Figure 10] It is a diagram showing a method for manufacturing the curing cap for the male joint in an embodiment of the present invention (Part 1). [Figure 11]This figure (part 2) shows a method for manufacturing a protective cap for a male connector according to an embodiment of the present invention. [Figure 12] This is a cross-sectional view showing a modified example of a protective cap for a female joint in an embodiment of the present invention. [Figure 13] This is a cross-sectional view showing a modified example of a protective cap for a male connector in an embodiment of the present invention. [Modes for carrying out the invention]

[0024] This invention relates to a protective cap to be attached to a mechanical joint member joined to the end of a steel pipe, and to a method for manufacturing the protective cap. The steel pipe to which the mechanical joint member to which the protective cap is attached is joined can be used for any purpose, such as a steel pipe pile, but in this embodiment, a steel pipe column used as a column material such as a structural column will be used as an example, and the details will be explained with reference to Figures 1 to 13.

[0025] The steel pipe column 1 to be fitted has a diameter of approximately 1300 to 2000 mm, and as shown in Figure 1, it comprises a steel pipe body 10 and a mechanical joint member consisting of a cylindrical body that connects the steel pipes in the axial direction. The mechanical joint member is composed of a female joint 11 having a female thread 11a on the inner circumferential surface of one end of the steel pipe body 10, and a male joint 12 having a male thread 12a on the outer circumferential surface of the other end. When the steel pipe column 1 is positioned in an upright position along the vertical direction, the female joint 11 is positioned at the upper end and the male joint 12 is positioned at the lower end. However, the steel pipe column 1 may also be positioned so that the male joint 11 is located at the upper end and the female joint 12 is located at the lower end when it is positioned in an upright position along the vertical direction.

[0026] As shown in Figure 2, the female joint 11 has a female joint steel pipe connecting portion 11b that forms the same annular shape as the steel pipe body 10 and connects to the steel pipe body 10, and an enlarged diameter portion 11c provided at the tip side of the female joint steel pipe connecting portion 11b, which is the upper end side of the female joint steel pipe connecting portion 11b, and has a larger outer diameter than the female joint steel pipe connecting portion 11b. The inner diameter of the enlarged diameter portion 11c is formed to be larger than the inner diameter of the female joint steel pipe connecting portion 11b, and a female thread 11a is provided on its inner circumferential surface. A non-female thread portion 11d is provided at the tip of the inner circumferential surface, and when fitting the steel pipe columns 1 together, the non-female thread portion 11d is inserted before the female thread 11a.

[0027] The inner diameter of the female thread 11a is larger than the inner diameter of the female joint steel pipe connecting portion 11b, and the inner diameter of the male joint 12 to be screwed into and the inner diameter of the female joint steel pipe connecting portion 11b are configured to be the same. For this reason, a female-side stepped surface 11e is provided at the boundary between the female joint steel pipe connecting portion 11b and the female thread 11a, and the female-side stepped surface 11e faces the tip portion 12f of the screwed male joint 12.

[0028] As shown in Figure 3, the male joint 12 has a male joint steel pipe connecting portion 12b that forms the same annular shape as the steel pipe body 10 and connects to the steel pipe body 10, and a male thread 12a provided on the outer circumferential surface of the tip end of the male joint steel pipe connecting portion 12b that screws into the female thread 11a. In addition, the tip end of the outer circumferential surface is provided with a non-male thread portion 12c that does not have the male thread 12a, and when fitting the steel pipe columns 1 together, the non-male thread portion 12c is inserted into the non-female thread portion 11d before the male thread 12a.

[0029] Between the male joint steel pipe connecting portion 12b and the male thread 12a, an annular projection 12d is provided that protrudes around the entire circumference on the outer side. At the boundary between the annular projection 12d and the male thread 12a, a male joint side load transmission surface 12e is provided, which forms a stepped surface that protrudes from the outer surface. The male joint side load transmission surface 12e is such that the female joint side load transmission surface 11f, which is the tip of the female joint 12 screwed with the male joint 11, faces the steel pipe column 1 in the axial direction, and when a load is applied in the axial direction, the male joint side load transmission surface 12e and the female joint side load transmission surface 11f press against each other to transmit the load. In this embodiment, both the male joint side load transmission surface 12e and the female joint side load transmission surface have an inclination that moves toward the female joint 11 side toward the outer side.

[0030] As shown in Figure 4, the protective cap 2 for the female fitting 11 has a female thread contact portion 2a that abuts against the entire circumference of the female thread 11a from the inner side, a non-female thread contact portion 2b connected to the female thread contact portion 2a that abuts against the entire circumference of the non-female thread portion 11d from the inner side, a female fitting tip facing portion 2c connected to the non-female thread contact portion 2b that faces the female fitting side load transmission surface 11f of the female fitting 11 in close proximity, and an enlarged diameter contact portion 2d connected to the female fitting tip facing portion 2c that abuts against the entire circumference of the outer surface of the enlarged diameter portion 11c. In other words, the protective cap 2 for the female fitting 11 sandwiches the tip side of the female fitting 11 and covers it from the inner side to the outer side over its entire circumference.

[0031] The female thread contact portion 2a is connected from a position that contacts or is close to the female side stepped surface 11e, and the length extending from the female joint tip opposing portion 2c is formed to be longer than the enlarged diameter contact portion 2d. Furthermore, as shown in Figure 5, the protective cap 2 for the female joint 11 is ring-shaped, and its inside penetrates the steel pipe column 1 in the axial direction. In the protective cap 2 for the female joint 11 of this embodiment, the female thread contact portion 2a and the non-female thread contact portion 2b face the inner circumferential surface of the female joint and correspond to the circumferential surface protective portion that protects the inner circumferential surface, the female joint tip opposing portion 2c is connected to the circumferential surface protective portion and faces the tip of the female joint and protects the tip, and the enlarged diameter contact portion 2d is connected to the tip protective portion and corresponds to the circumferential surface opposing portion that faces the circumferential surface protective portion around its entire circumference.

[0032] As shown in Figure 6, the protective cap 3 for the male connector 12 has a male thread contact portion 3a that abuts against the entire circumference of the male thread 12a from the outer circumference, a non-male thread contact portion 3b connected to the male thread contact portion 3a that abuts against the entire circumference of the non-male thread portion 12c from the outer circumference, a male connector tip opposing portion 3c connected to the non-male thread contact portion 3b that abuts against and faces the tip portion 12f of the male connector 12, and an inner surface contact portion 3d connected to the male connector tip opposing portion 3c that abuts against the entire circumference of the inner surface 12g. In other words, the protective cap 3 for the male connector 12 also sandwiches the tip side of the male connector 12 and covers it all around, from the inner circumference to the outer circumference.

[0033] The male screw contact portion 3a is connected from a position close to the load transmission surface 12e on the male joint side, and the length extending from the male joint tip opposing portion 3c is formed to be longer than the inner circumferential contact portion 3d. Furthermore, as shown in Figure 7, the protective cap 3 for the male joint 12 is ring-shaped, and its inside penetrates the steel pipe column 1 in the axial direction. In the protective cap 3 for the male joint 12 of this embodiment, the male screw contact portion 3a and the non-male screw contact portion 3b correspond to the circumferential protective portion that faces the outer circumferential surface of the male joint and protects the outer circumferential surface, the male joint tip opposing portion 3c corresponds to the tip protective portion that is connected to the circumferential protective portion and faces the tip of the male joint and protects the tip, and the inner circumferential contact portion 3d corresponds to the circumferential facing portion that is connected to the tip protective portion and faces the circumferential protective portion around its entire circumference.

[0034] The protective caps 2 and 3 for the female fitting 11 and male fitting 12 are both reinforced on the surface by a reinforcing layer. The reinforcing layer is formed by coating a thin outer material 7 made of synthetic resin with a higher hardness than the interior, and the interior is made of a cushioning material 5 made of soft polyethylene resin, for example, which has elasticity when solidified. In addition, a UV-blocking agent 4 is applied to the surface of the outer material 7 as a UV-blocking layer.

[0035] The method for manufacturing the protective cap 2 for the female fitting 11 is as follows: First, as shown in Figure 8(a), the female fitting 11 to be fitted is positioned with the female fitting steel pipe connecting portion 11b facing downwards and the female fitting side load transmission surface 11f facing upwards, and any dirt or foreign matter is removed from the surfaces of the female thread 11a, the non-female thread portion 11d, the female fitting side load transmission surface 11f, and the enlarged diameter portion 11c that will be covered by the protective cap 2.

[0036] Next, as shown in Figure 8(b), sheet-shaped cushioning material 5a and 5b, cut to an appropriate size from the raw material of sheet-shaped cushioning material 5, are applied to the female thread 11a and non-female thread portion 11d from the inside of the female joint 11. Then, the cushioning material 5a and 5b are applied around the entire circumference along the curved surface of the female thread 11a and non-female thread portion 11d, and the ends of the cushioning material 5a and 5b in the circumferential direction are compressed and brought together, thereby bracing the cushioning material 5a and 5b in the circumferential direction and maintaining the state in which the applied cushioning material 5a and 5b conform to the curved surface of the female thread 11a and non-female thread portion 11d. At this time, the cushioning materials 5a and 5b are placed on the stepped surface 11e on the female side and are positioned against the curved surfaces of the female thread 11a and the non-female thread portion 11d, with their upper ends protruding above the female joint side load transmission surface 11f of the female joint 11 by the height of the female joint tip opposing portion 2c.

[0037] Next, as shown in Figure 8(c), a sheet-like cushioning material 5c is formed to the width of the height of the female joint tip facing portion 2c, placed on the female joint side load transmission surface 11f of the female joint 11, and adhered to the portion of the cushioning material that protrudes beyond the female joint side load transmission surface 11f along the curved surface of the non-female thread portion 11d using, for example, double-sided tape. At this time, double-sided tape 6 is provided in advance on both sides in the diametrical direction of a member whose height and width have been appropriately adjusted for the cushioning material 5c placed on the female joint side load transmission surface 11f of the female joint 11. Then, one side of the double-sided tape 6 adheres the cushioning material 5c placed on the female joint side load transmission surface 11f of the female joint 11 to the protruding portion of the cushioning material 5b that follows the curved surface of the non-female thread portion 11d. Figure 8 shows an example in which the buffer material 5c constituting the female joint tip opposing portion 2c is formed by connecting two members in the diametrical direction of the female joint 11. However, it may also be formed from one member or from three or more members.

[0038] Next, as shown in Figure 8(d), the sheet-like cushioning material 5d is cut to a length equal to the combined height of the enlarged diameter contact portion 2d (Figure 4) and the cushioning material 5c placed on the female joint side load transmission surface 11f, wrapped around the outer circumference of the enlarged diameter portion 11c, and adhered to it using the double-sided tape 6 provided on the cushioning material 5c placed on the female joint side load transmission surface 11f of the female joint 11. In this way, the female thread 11a, the non-female thread portion 11d, the female joint side load transmission surface 11f, and the enlarged diameter portion 11c are covered with cushioning materials 5a to 5d.

[0039] Next, as shown in Figure 8(e), an outer surface, such as the outer circumferential surface, inner circumferential surface, and top surface, which are exposed to the outside of the cushioning materials 5a to 5d attached to the female fitting 11, is coated with a two-component curable synthetic resin that becomes harder than the cushioning materials 5a to 5d when solidified, and solidified to form the outer surface material 7. As shown in Figure 9(a), after the outer surface material 7 is formed, an ultraviolet inhibitor 4 is applied to its surface.

[0040] After the UV-blocking agent 4 has dried, as shown in Figure 9(b), the unfinished female joint protective cap 20 is removed from the female joint 11, and as shown in Figure 9(c), the unfinished female joint protective cap 20 is placed on the protective material 8 made of wood or the like that has been installed, with the cushioning material 5c side facing down, which is positioned on the female joint side load transmission surface 11f.

[0041] Subsequently, a two-component curable synthetic resin is applied to the outer surfaces of the unfinished female joint curing cap 20, specifically the parts where the outer surface material 7 is not provided, i.e., the female thread 11a, the non-female thread portion, the female joint side load transmission surface 11f, the parts facing the enlarged diameter portion 11c, and the upper end surface when it is placed on the protective material 8, and solidified to form the outer surface material 7. After the outer surface material 7 is formed, an ultraviolet inhibitor 4 is applied to its surface as shown in Figure 9(e). Once the ultraviolet inhibitor 4 dries, the curing cap 2 for the female joint 11 is completed.

[0042] The method for manufacturing the protective cap 3 for the male fitting 12 is almost the same as the method for manufacturing the protective cap 2 for the female fitting 11. Specifically, as shown in Figure 10(a), the male fitting 12 to be fitted is positioned with the male fitting steel pipe connecting portion 12b facing downwards and the tip portion 12f facing upwards, and dirt and foreign matter are removed from the male thread 12a, non-male thread portion 12c, tip portion 12f, and inner circumferential surface 12g that will be covered by the protective cap 3.

[0043] Next, as shown in Figure 10(b), a sheet-like cushioning material 5e, similar to the protective cap 2, is cut to an appropriate size and applied from the inside of the male joint 12 to cover the entire circumference of the inner circumferential surface 12g. The ends of the cushioning material 5e are compressed in the circumferential direction and brought together, maintaining a state that conforms to the curved surface of the inner circumferential surface 12g. At this time, the upper end of the cushioning material 5e protrudes above the tip portion 12f of the male joint 12 by the height of the male joint tip opposing portion 3c.

[0044] Next, as shown in Figure 10(c), a sheet-like cushioning material 5f is formed to the width of the height of the male joint tip facing portion 3c, placed on the tip portion 12f of the male joint 12, and adhered to the portion of the cushioning material 5e that protrudes beyond the tip portion 12f along the curved surface of the inner circumferential surface 12g using, for example, double-sided tape 6.

[0045] Next, as shown in Figure 10(d), sheet-like cushioning materials 5g and 5h are cut to match the male thread 12a and the non-male thread portion 12c. Cushioning material 5g is wrapped around the outer surface of the non-male thread portion 12c and adhered to it using the double-sided tape 6 provided on cushioning material 5f, which is placed on the tip portion 12f of the male connector 12. Then, cushioning material 5h is placed so as to span both cushioning material 5g and the male thread 12a, and is attached to cushioning material 5g. In this way, the female thread 11a, male thread 12a, non-male thread portion 12c, tip portion 12f, and inner circumferential surface 12g are covered with cushioning materials 5e to 5h.

[0046] Next, as shown in Figure 10(e), a two-component curable synthetic resin is applied to the outer surfaces of the cushioning materials 5e to 5h attached to the male connector 12, including the outer circumferential surface, inner circumferential surface, and top surface, which are exposed to the outside, and solidified to form the outer surface material 7. After the outer surface material 7 is formed, an ultraviolet inhibitor 4 is applied to its surface, as shown in Figure 11(a).

[0047] After the UV-blocking agent has dried, as shown in Figure 11(b), the unfinished male joint protective cap 30 is removed from the male joint 12, and as shown in Figure 11(c), the unfinished male joint protective cap 30 is placed on the installed protective material 8 with the cushioning material 5f side facing down, which is positioned on the tip portion 12f.

[0048] Subsequently, a two-component curable synthetic resin is applied to the outer surface of the unfinished male joint protective cap 30, specifically to the parts where the outer surface material 7 is not provided, i.e., the male thread 12a, the non-male thread portion 12c, the tip portion 12f, and the part that was in contact with the inner circumferential surface 12g, and allowed to solidify to form the outer surface material 7. After the outer surface material 7 is formed, an ultraviolet inhibitor 4 is applied to its surface as shown in Figure 11(d). Once the ultraviolet inhibitor 4 dries, the protective cap 3 for the male joint 12 is completed.

[0049] The protective cap 2 for the female fitting 11 of this embodiment has a female thread contact portion 2a that faces the female thread 11a of the female fitting 11 and a female fitting tip facing portion 2c that faces the female fitting side load transmission surface 11f of the female fitting 11. Therefore, by attaching the protective cap 2 to the female fitting 11, it is possible to suppress damage to the female thread 11a and the female fitting side load transmission surface 11f, and to suppress the adhesion of foreign matter to the female thread 11a and the female fitting side load transmission surface 11f.

[0050] Furthermore, the protective cap 2 for the female fitting 11 has a continuous female screw contact portion 2a and a female fitting tip opposing portion 2c, and also has an enlarged diameter contact portion 2d that is continuous with the female fitting tip opposing portion 2c and abuts over the entire circumference of the outer surface of the enlarged diameter portion 11c. In other words, the protective cap 2 for the female fitting 11 has a continuous female screw contact portion 2a and an enlarged diameter contact portion 2d that are provided over the entire circumference, and the female screw contact portion 2a and the enlarged diameter contact portion 2d are provided facing each other with a gap in the diametrical direction of the female fitting 11, so that the female fitting tip opposing portion 2c forms the bottom and the female screw contact portion 2a and the enlarged diameter contact portion 2d face each other, forming an annular groove. For this reason, it is possible to cover the female fitting 11 so as to accommodate it along the circumferential direction. Therefore, when the protective cap 2 is attached, the female fitting 11 is covered all around its tip, from the inner circumference to the outer circumference. This prevents foreign matter from entering the female thread 11a and the female fitting side load transmission surface 11f from the space between the female thread contact portion 2a and the female fitting tip opposing portion 2c, and from the space between the female fitting tip opposing portion 2c and the enlarged diameter contact portion 2d.

[0051] The protective cap 3 for the male connector 12 of this embodiment has a male thread contact portion 3a that faces the male thread 12a of the male connector 12 and a male connector tip facing portion 3c that faces the tip portion 12f of the male connector 12. Therefore, by attaching the protective cap 3 to the male connector 12, it is possible to prevent damage to the male thread 12a and tip portion 12f, and to prevent foreign matter from adhering to the male thread 12a and tip portion 12f.

[0052] Furthermore, the protective cap 3 for the male connector 12 has a male screw contact portion 3a and a male connector tip opposing portion 3c that are continuous, and also has an inner circumferential surface contact portion 3d that is continuous with the male connector tip opposing portion 3c and abuts over the entire circumference of the inner circumferential surface 12g. In other words, the protective cap 3 for the male connector 12 has a male screw contact portion 3a and an inner circumferential surface contact portion 3d that are continuous with the male connector tip opposing portion 3c and extend over the entire circumference, and the male screw contact portion 3a and the inner circumferential surface contact portion 3d are provided facing each other with a gap in the diametrical direction of the male connector 12, so that the male connector tip opposing portion 3c forms the bottom and the male screw contact portion 3a and the inner circumferential surface contact portion 3d face each other, forming an annular groove. As a result, it is possible to cover the male connector 12 so as to accommodate it along the circumferential direction. Therefore, when the protective cap 3 for the male connector 12 is attached, the tip of the male connector 12 is covered all around, from the inner circumference to the outer circumference. This prevents foreign matter from entering the male thread contact portion 3a and the male connector tip facing portion 3c, and from entering the male thread contact portion 3c and the inner surface contact portion 3d, as well as preventing water from entering.

[0053] Furthermore, since the protective caps 2 and 3 are covered with an outer material 7 made of a resin whose surface is harder than the internal cushioning material 5, external impacts are protected by the hard outer material 7 and by the cushioning material 5, which is harder than the surface. This makes it possible to more reliably protect the female thread 11a and the female joint side load transmission surface 11f of the female joint 11 or the male thread 12a and tip 12f of the male joint 12. In addition, even when the protective caps 2 and 3 are removed from the female joint 11 or male joint 12 and stored individually, the outer material 7 can suppress deformation and damage due to external impacts. Furthermore, since an ultraviolet inhibitor 4 is applied to the surface of the outer material 7, it is possible to suppress the deterioration of the outer material 7 by ultraviolet rays.

[0054] Furthermore, the protective caps 2 and 3 are annular in shape and have an open inner surface, making them lighter than those with a closed inner surface. As a result, the protective caps 2 and 3 are easy to handle and can be easily attached to and removed from the female connector 11 or male connector 12.

[0055] Furthermore, since the protective caps 2 and 3 that were attached to the female joint 11 and male joint 12 are undamaged and free of foreign matter, it becomes possible to easily screw the male thread 12a of one of the two steel pipe columns 1 into the female thread 11 of the other steel pipe column 1 and tighten them securely.

[0056] Furthermore, according to the manufacturing method of the protective caps 2 and 3 of this embodiment, by covering the female thread 11a and the female joint-side load transmission surface 11f of the female joint 11 or the male thread 12a and tip portion 12f of the male joint 12 with the cushioning material 5, it becomes possible to easily position the cushioning material 5 according to the shape of the female joint 11 and the male joint 12, and it becomes possible to easily form an outer material 7 made of a resin layer with a higher hardness than the cushioning material 5 on its surface.

[0057] The protective caps 2 and 3 and the method for manufacturing protective caps 2 and 3 of the present invention are not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0058] For example, in the above embodiment, an example was described in which the protective cap 2 for the female fitting 11 is composed of a female screw contact portion 2a, a non-female screw contact portion 2b, a female fitting tip facing portion 2c, and an enlarged diameter contact portion 2d, but it is not limited to this. For example, as shown in Figure 12, the female side stepped surface protective portion 2e facing the female side stepped surface 11e may be formed by extending the female screw contact portion 2a toward the end of the steel pipe body 10, and furthermore, the inner circumferential surface contact portion 2f that abuts against the inner circumferential surface 11g on the steel pipe body 10 side of the female fitting 11 may be provided continuously with the female side stepped surface protective portion 2e.

[0059] In this case, when the two steel pipe columns 1 are connected, it is possible to prevent damage to the female stepped surface 11e facing the tip 12f of the male joint 12, and to prevent foreign matter from adhering to the female stepped surface 11e. Furthermore, since an inner circumferential surface contact portion 2f is provided, it is possible to prevent foreign matter from entering between the female stepped surface 11e and the female stepped surface protection portion 2e, and to prevent water from entering.

[0060] Furthermore, although an example has been described in which the protective cap 3 for the male joint 12 is composed of a male screw contact portion 3a, a non-male screw contact portion 3b, a male joint tip opposing portion 3c, and an inner circumferential surface contact portion 3d, it is not limited to this. For example, as shown in Figure 13, the male side stepped surface protective portion 3e facing the male joint side load transmission surface 12e may be formed by extending the male screw contact portion 3a toward the end of the steel pipe body 10, and furthermore, the annular projection contact portion 3f that abuts the outer circumferential surface of the annular projection 12d may be provided continuously with the male side stepped surface protective portion 3e.

[0061] In this case, when the two steel pipe columns 1 are connected, it is possible to prevent damage to the male joint-side load transmission surface 12e that faces the female joint-side load transmission surface 11f of the female joint 11, and to prevent foreign matter from adhering to the male joint-side load transmission surface 12e. Furthermore, since an annular projection contact portion 3f is provided, it is possible to prevent foreign matter from entering between the male joint-side load transmission surface 12e and the male side stepped surface protection portion 3e, and to prevent water from entering.

[0062] In the above embodiment, protective caps 2 and 3 attached to a female fitting 11 having an internal thread 11a and a male fitting 12 having an internal thread 12a have been described, but the embodiment is not limited to this. For example, a protective cap attached to a female fitting and a male fitting may be a female fitting and a male fitting to which a male fitting with a sleeve is fitted and connected. [Explanation of symbols]

[0063] 1 steel pipe column 2. Protective caps for female connectors 2a Female thread contact part (surrounding surface curing part) 2b Non-female thread contact area (circumferential curing area) 2c Female connector tip opposing part (tip curing part) 2d Enlarged diameter contact area (circumferential surface facing area) 2e Female side, opposite the stepped surface (stepped surface protection area) 2f Inner peripheral surface contact part 3. Protective caps for male connectors 3a Male thread contact part (surrounding surface curing part) 3b Non-male thread contact part (surrounding surface curing part) 3c Male connector tip opposing part (tip protection part) 3D inner surface contact area (surface facing area) 3e Male side, opposite the stepped surface (stepped surface protection part) 3f Annular projection contact area 4. UV protection agent (UV protection layer) 5, 5a~5h buffer material 6. Double-sided tape 7 External material (reinforcement layer) 8. Protective material 10 Steel pipe body 11 Female connector (mechanical connector component) 11a Female thread 11b Female joint steel pipe connection 11c Expanded diameter part 11d Non-female threaded section 11e Female side stepped surface 11f Female joint side load transmission surface 11g Inner surface 12 Male connectors (mechanical connector components) 12a Male thread 12b Male joint for steel pipe connection 12c Non-male threaded section 12d Annular projection 12e Male joint side load transmission surface 12f Tip 12g inner surface 20 Unfinished Female Fitting Protective Cap 30 Unfinished male connector protective cap

Claims

1. A protective cap is attached to the female joint of a mechanical joint member which is joined to the end of a steel pipe, connects the steel pipe in the axial direction, and comprises a male joint and a female joint made of a cylindrical body having outer and inner surfaces parallel to the outer and inner surfaces of the steel pipe, A circumferential curing portion that contacts the inner circumferential surface of the cylindrical body, A tip curing section that is continuous with the circumferential curing section and abuts against the tip of the cylindrical body, It comprises a circumferential facing portion that is continuous with the tip curing portion and faces the circumferential curing portion across the cylindrical body, The circumferential curing portion is characterized by a sheet-like cushioning material made of polyethylene resin being applied along the curved surface of the cylindrical body over the entire circumference of the inner circumferential surface, and the ends of the sheet-like cushioning material in the circumferential direction being compressed and butted together in the circumferential direction.

2. A protective cap to be attached to the male joint of a mechanical joint member which is joined to the end of a steel pipe and connects the steel pipe in the axial direction, and which has a male joint and a female joint made of a cylindrical body having an outer and inner surface parallel to the outer and inner surfaces of the steel pipe, A circumferential curing portion that contacts the outer surface of the cylindrical body, A tip curing section that is continuous with the circumferential curing section and abuts against the tip of the cylindrical body, It comprises a circumferential facing portion that is continuous with the tip curing portion and faces the circumferential curing portion across the cylindrical body, The protective cap is characterized in that the circumferential surface facing portion is formed by applying a sheet-like cushioning material along the curved surface of the cylindrical body over the entire circumference of the inner circumferential surface, and the ends of the sheet-like cushioning material in the circumferential direction are compressed and abutted together in the circumferential direction.

3. A protective cap to be attached to the male or female joint of a mechanical joint member which is joined to the end of a steel pipe and connects the steel pipe in the axial direction, and which has a male joint and a female joint made of a cylindrical body having an outer and inner surface parallel to the outer and inner surfaces of the steel pipe, A circumferential curing portion that contacts the outer or inner circumferential surface of the cylindrical body, A tip curing section that is continuous with the circumferential curing section and abuts against the tip of the cylindrical body, A circumferential facing portion that is continuous with the tip curing portion and faces the circumferential curing portion across the cylindrical body, Equipped with, A reinforcing layer is provided on the outer surface of the circumferential curing section, the tip curing section, and the circumferential facing section. The protective cap is characterized in that the outer surface includes the surface facing the cylindrical body and the surface exposed to the outside when attached to the cylindrical body.

4. In the protective cap according to claim 3, A protective cap characterized in that an ultraviolet-preventive layer is laminated on the surface of the reinforcing layer.

5. In the protective cap according to any one of claims 1 to 3, A protective cap characterized in that the circumferential protective portion abuts against at least the threaded portion provided on the cylindrical body.

6. In the protective cap according to any one of claims 1 to 3, A protective cap characterized by comprising a stepped surface protective portion formed by extending the base end side of the circumferential surface protective portion, and facing a stepped surface that protrudes from the outer or inner circumferential surface of the cylindrical body.

7. In the method for manufacturing a protective cap according to claim 3, A method for manufacturing a protective cap, characterized by covering the outer or inner circumferential surface of the cylindrical body and the tip of the cylindrical body with a cushioning material, and forming the circumferential protective portion and the tip protective portion to be continuous.

8. In the method for manufacturing a protective cap according to claim 7, A method for manufacturing a protective cap, characterized by applying a curable resin to the outer surfaces of the circumferential protective portion and the tip protective portion to form the reinforcing layer.

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